uploading code

hey guys,
i'm very new to arduino and is just wrote my first code, but because of some issues with my computer i had to make it in online editor. but the issue is when i try to upload the code to my arduino uno and make it run the online editor doesn't find my arduino uno eventhough when i plug my arduino uno in to my pc it turns on and gets power.

any advice?

(deleted)

Does your computer see the UNO in the device manager (or equivalent on other OS) ?

Just seeing LED’s light up doesn’t always mean it is connected to the computer it simply means that the board is getting power.
Ensure cables are firmly plugged in and where possible use a USB 2.0 port.

Bob.