Back Exercises?

I have been having back pains lately, due to the fact I have a bad posture. I have a problem with my collar bone that causes it to painfully come out of socket when I extend my shoulders back, so when I would do things someone without the problem would, I use the muscles in my chest where someone else would use their back. I asked a trainer at a gym about it...so this is where this info came from. Unfortunately I cant afford a trainer and he wouldn't tell me any exercises. This problem has caused my chest to draw my shoulders together and make my posture horrible, thus making my upper back hurts from just standing. What are some simple back exercises I can do at home?

http://www.1backpain.com/back_exercises.htm

http://orthoinfo.aaos.org/fact/thr_report.cfm?Thread_ID=17&topcategory=Spine

to strengthen your back there are some very simple excercises that you can do with dumbells.

Trapezius (the muscles between your neck and your shoulders): Shrugs

Take some weight in each dumbell (you can probably use alot, i could do over 130lbs when i had just started working them out.) then you just shrug your shoulders up, it's not necessary to touch your ears, you just need to do your strongest range, it'll stimulate growth and increase in strength.

Lower back (don't know the scientific name): dead lifts

Now for this one it is INCREDIBLY important to have good form. you NEVER EVER put weight on your back when it's parallel to the ground. get some weighted dumbells (you can probably use about the same weight as for your shrugs) put them in front of you, bend down to pick them up, bending you knees a bit so you don't bend down too much, then stand up straight. to repeat just bend your knees a bit and bend your back over a bit, then stand up straight.

Latissimus dorsii (mid-back, the ones that protrude on the side): Chin ups or pull ups.

Get a chinup bar, make one yourself, or just grab something that you can hang from. if you use a wider grip you'll target different parts of your lats but whatever grip you use will work every part to some extent. just do as many as you can, work your way up.

You can also use a barbell instead of dumbells for the first 2, in fact it's probably better but barbells are more expensive and for what you're trying to do dumbells will do just fine. make sure you use a weight that you can only do 8-10 reps of. do 2 or 3 sets, depending on how much energy you have. to start off however i'd get a light weight until you get used to the movement, it's better to not make much improvement and get good form than to kill your back, this is a "dangerous" area to work if you don't have good form.