whenever i press on the brake, my parking lights come on as well as my gage cluster and clock dims etc.
why is it doing this or what could i do to fix this problem?

 

If the guages are dimming while the car is running, that is a sign of a weak alternator/battery. If your testing it with just the key on, then thats pretty natural.

If your parking lights come on instead of brake lights, it may just be that your light plugs are switched in the wrong places in the tail light.

Good luck.