Looks like I have the same model trainer as you (although it looks like you got the RTF; I have the ARF). Anyway, I used my wifes hair dryer and iron to work out the wrinkles. I ended up having to use a t-pin to poke a small hole on the covering to let the air escape. I then put a drop of CA over the hole to keep fuel out.

Just a side note; a guy at my club was flying the RTF version. He entered a bank (about 45 degrees) and his wings folded. Make sure you use plenty of epoxy in the wing joint. If there is any gap, fill it with CA. He lost his plane and motor (don't know about the RX and servos) because he only applied epoxy to about half the wing joint.