MIT App Inventor helps anyone, regardless of experience, build fully functional apps.

Code.org provides courses to help you learn programming. It also has App Lab, which teaches you how to design, build, and share apps.

StackOverflow is a question and answer site. You can find answers to many of your questions that come up during app building on this site.

Thunkable lets you build your own app for iOS or Android using a drag and drop interface.