intelectual

Hey you guys, I guess this is the right forum to post this one in...here is my problem..

First let me tell you this, I am not very mechanically inclined, so be easy.
I replaced the rear break SHOES (drum brakes) on my Civic (the beater) and didn't think that I messed up anything until when I got in and started driving it.

Now they don't seem to be working anymore at all. I have to about stand up on the car for it to stop....I checked the fluid but it's full so I have no idea what could be the problem at this point....

Damn, I knew I should have just taken it to a garage..I hate drum brakes!!

Does anyone have any suggestions on what I should try to do to get this fixed.

Also does anyone know of a good product to clean my oil system? Even after I just change my oil and then check it, it is almost black....I think that it needs some kind of treatment but don't know of any good ones.

Thanks you guys