Room Colours..?

Alrighty, so my room right now is painted a lightish purple. I am not gonna repaint the whole room. But, instead I want to do some patterns or designs. What are some easy patterns to do? Also, I don't know what colors to use. I was hoping on doing yellow and green (my two fave. colours). But, when I looked online for bed spreads and pillows there were none that were the right color. So, what other two colors would look good? Also, what is a store that sells not-super-expensive bed stuff? Thanks so much!!!