1
Get some cheap mirror (or picture frame) Mine is from Ikea, and didn't even cost 2 Euro.
2
Paint it any color you want and cut your cd's in to little pieces.
Start glueing them onto the frame, in any pattern you want.
3
Add more...
4
...and more
5
And hang it on your wall! (Yeah I still need to clean the mirror part, there's glue on it.)