About licenses and copyrights I had to use my own images as backgrounds: I took several pictures of my surroundings with my Samsung Galaxy Note 2 N7100 and then added to them some special FX and filters.
I made also all the characters: the emoticon (mascotte of the app) unsing GIMP 2 and the evil heads. These ones are modified pictures of me.
For the voices sounds I recorded my voice and then modified with an android application on my mobile.
In the "credits" scene of my game there are references to some licensed elements.
I'm not a musician so I used some music loops from a website that offers free royalties music loops (for commercial and non-commercial use): nice music for YouTube videos, applications and also other kinds of projects.
You can visit this amazing site here: http://www.partnersinrhyme.com
If you are a beginner like me you'll find very useful resources by navigating on the web: not everything requires payments. With some efforts you can find free solutions for your needs just like me.
Expecially about programming: if you use Corona SDK or other platforms (Eclipse, App Inventor, etc.) just check their forums, specialized websites or YouTube tutorials.