i really wanna bag a 68 or so c-10 but u have to z the frame and i have no clue what that is? help me out?  

Let’s just say you want to z the frame 3"
Right in front of the fire-wall you cut the frame. You would raise the front of the frame where the motor sits 3" and weld it back to the rest of the frame. So now the motor and the front of the frame are 3" higher than the cab and rest of the frame. There will be some gaps that you will need to make filler plates to box the frame back in. Now move to the front horns of the frame where the radiator support mounts. You will cut the front horns free and lower them 3" so that it will line up with the rest of the body. You will need to box the frame back in here too.

Now let’s say you want to z the frame 3" and body drop the truck 3"

You would basically do the same except on the front horns. 3"Z + 3" BD =6" so instead of just lowering the front horns 3" you would need to lower them 6"