my car doessnt stop well should i take a look at the drum brakes or do they automatically adjust?

They should automatically adjust if you back up and brake hard. However if they are badly out of adjustment, inspect them and adjust them back into range. Then the auto adjuster should pick up the adjusting from there.

how does that work (going in reverse)? Thats intresting?

Honestly...I've never really looked into it. Someone that has will be along soon. It does though, as long as the parts are lubricated properly and in good shape.

Automatic adjusters aren't worth a hill of beans when they get crudded up with brake dust. Pull the drums and adjust the spur-like device until the drums BARELY go back over the shoes. If you go too far, back off one notch.