Depends on multiple things, most major things that determine your best way to learn are (in my opinion and I can only speak from personal experience in learning how to program):
- Do you have previous experience with programming in any language? (NO html + css are not programming languages)
Yes: Just take a look at the API and try to puzzle stuff together (is what I did)
No: Look for basic Java programming courses/tutorials etc. To learn how the language works.
- Do you prefer text/video resources to learn things?
Text: There are some good threads in the Tutorials section of the forum.
Video: There are some good videos on Youtube which are decently old but most knowledge still applies and cna be transfered, only the API changed basically.
some general tips:
- Don't start big, first learn to walk before you start to run and even before that learn how to crawl.
- If you cannot figure something out, don't be afraid to ask (granted you should have googled first)
- Just do it, and give it your best shot.
EDIT: I forgot a important one, - Learn it for fun and yourself, nothing else. And certainly don't do it just for the sake of other people.