Using cammy defensively can be a bit of a challenge, since she’s pretty offensive-related and mix-up based.
If you want to be defensive, just sit back. It’s not really something that can be taught, defense is something you have to learn on your own. To put it bluntly, I can teach somebody how to attack, and how to rush somebody down and mix them up. But I can’t teach them, “See this? Yeah, block that.” That’s something that’s self-taught with experience and time.
If you play online, instead of being aggressive, be defensive, patient, and sit back. Let your opponent come to you, and try to punish their whiffed attacks or dropped links. If you rush them, you won’t be learning anything. Be patient, sit back, and let them make the mistake.
Oh, and as for a new starter character? Pick who you want to use. Go through the cast, and whoever appeals to you, pick them up and stick with them. Some characters will be harder to use them some, and others will be easier. Pick up whoever you feel you are having the most fun with, and stick with it!
Are you on PSN or XBL? If you’re on PSN shoot me a friend request and I’ll see what I can do to help you out. Quebert69 is my ID.
Oh, and welcome, btw.