Welcome,
Start with spending a week on the tutorial pages of the arduino.cc website. BUild the code and make changes to it and see the effect. That is a good way to start to understand the ins and outs of the arduino language.
Also go through the reference pages, although there are errors on them they are a great source of information.
Finally, in the upper right corner of the forum is a search box. You can search older threads as the forum contains a lot of wisdom (and a few bugs too).
Then there is the playground where you can find more about libraries, sensors etc.
And if that all doesn't help you can always ask on the forum, try to find the best matching section, and please read the top messages on several section (about how to post, and some common answers.