Welcome to the Arduino forum. If you are making your first post you will have been re-directed here where we explain how to get the best out of this forum, please read and follow the instructions below.
The people who try to help with your project are volunteers doing this for free in their spare time. If you follow these guidelines it helps us to help you and get your project working quickly.
Without the correct information it is difficult or impossible to give you the help you need and all that happens is a long exchange of messages while we try to get the information we need to help you. This is frustrating for you and for us.
Below are some things we need which are often missed by people posting for the first time
Choose the right section of the Forum There are lots of different sections to choose from. Choosing the right one is important because not everyone who might be able to help you reads every section. Some questions might reasonably fit in to more than one section but please do not post the same question in 2 or more different sections. This just wastes your time and ours as different people will be providing different answers in different places. For this reason it is against the forum rules and will incur the wrath of the moderators when they see it.
Hardware: We need to know exactly what hardware you have. We need to know what Arduino board (or other brand, such as ESP32) you are using and exactly what other hardware you are connecting it to. The more details we have the easier it is to help.
If you are using something that is a non-Arduino product then it helps to have a link to its technical data sheet or a link to where you bought it.
Code problems: We can only find problems in code we can see. Please supply your complete code in code tags > More about posting code and using code tags.
Posting a snippet of code is generally useless. The problem is usually in another part of the program.
Before posting code please use Tools / auto format at the top of the IDE. It makes the code much easier to read and you will probably find it very helpful yourself. Once you've done that use edit / copy for forum.
Always use code tags (>) when posting code or compiler error messages. Using code tags makes the code easier to read and easy to copy. Not using code tags means some of the code gets displayed with smiley faces and other stuff that should not be there. Be aware that there is a limit of 9000 characters for a post and if your code takes you above this limit then you can add your .ino file as an attachment. However it will be much easier to help you if you can write a short program that illustrates the problem you are having and post that.
Please don't post an image of code instead of the code itself, or an image of error messages instead of the error messages themselves.
It is very important to be clear about what is expected from code and what happens instead. Code ALWAYS works, that is the nature of code. Whether it does what you expect is a different thing altogether. We need to know what you expected the code to do and what happened instead. More about posting code and common code problems.
Schematics or circuit diagrams: The language of electronics is a schematic or circuit diagram. Long descriptions of what is connected to what are generally useless. A schematic is a drawing of what connects to what, please make one and photograph it. We don't mind if it's hand drawn, scruffy and does not use the correct symbols. Please don't post Fritzing diagrams. They may look nice but they are very easy to misinterpret
If you want to use computer software to create a schematic then you might like to try either Eagle or KiCad. More about creating a schematic of your project including how to upload an image.
General: Please try to avoid posting links to other sites where code or photos or schematics are hosted. Most of us will not follow such links, partly because of the risk that they hold malware or other unwanted content, partly to maintain everything on this site for the benefit of future users looking for an answer to a similar question and partly because we feel that if you want our help you should provide everything we need on this site not expect us to go hunting elsewhere for it.
TYPING IN ALL UPPER CASE is considered to be SHOUTING. It won't get you an answer any quicker, it will just annoy people.
Research Please do some research before posting. Most beginner problems have already been dealt with on the Forum so please use the forum search tool and the Arduino help centre to try and find an answer to your question. You can also use your favourite search engine to find answers too.
Be specific: Please ask a specific question about the problem you are having so we can provide a clear, specific answer.
If you don't understand some of the advice that you get, please say so. Then we can explain in more detail.
About us: Those of us answering questions have a wide variety of backgrounds and electronics knowledge, some through working in electronics, some through electronics as a hobby, some both. Most of us are not trained as teachers so probably miss the finer points of how to teach and explain things effectively. We are not, with the odd exception, employees or representatives of Arduino.
About you: We only know about you and your project what you tell us. If you tell us your level of experience with electronics or micro-controllers, we can tailor our answer to your level of knowledge. We also don't know if you have problems with English or language or communications in general unless you tell us. We can be sympathetic about things we know about, but if you don't tell us we don't know.
More information: There is enough information above to make a decent first post. There is more help in the long version of this tutorial but maybe you think that's an awful lot to read through.
Making your first post: Now please go to the forum index, select the right section and make your first post.
Credits Much of this tutorial has been inspired by or copied from the original forum instructions created by Nick Gammon. My thanks to Ballscrewbob, Robin 2 and Idahowalker all of whom have provided a great deal of support and feedback, without which this tutorial would contain far more errors than it does and would be a lot less clear than it is.