I am a contractor with a fair amount of knowledge, but have never plumbed a bathroom in a basement. I have a 4" sewer line located in the center of my bathroom layout. The sewer line is at its lowest point in the basement near the house trap. I know I will need a
3" line for the toilet, a 2" line for the shower and an 1 1/2" line for the sink. I have no problem with the plumbing for the sink, but I am not quite sure where the vent for my shower and my toilet will come from beneath the slab.

Can someone give me a basic diagram showing the plumbing beneath the slab.

Can someone please offer me a little help on this diagram. Any help would be appreciated.