Problems skinning with Photoshop

[vastator]

I'm using a trial version of Photoshop and I've hit a couple of snags. The unit cards have come out fine, but the textures aren't quite right. When I save a modified texture it drops from 86k to only 65k. Also, there's one soldier on the extreme left of the unit with a black rectangle around his shield.

Can someone tell me (a) what's causing these problems and (b) which of this site's Photoshop tutorials is the most idiot-friendly?

[vastator]

Problem solved! I found a thread on this problem and player1's advice did the trick.