I want to get a processor...Where do I connect the surrounds

Center channel surrounds.
I'll have to think about that.

The Marantz sr7013 has 9 channels of amplification & is a complete 9.2 channel surround processor.First I would ask why add an external surround processor to this?
IF you must use separates you will need an external amplifier as well,the Marantz can be used as a PreAmp/Surround processor BUT NO capability to use the amplification section only(which would be labeled as "9.2 CH Amp IN"I believe...
 

Maybe ask again OP what do you want to do?

A center only.

Two rears only.

That is how it reads..

Regards

Don’t ask, don’t tell.

Actually it reads:.
"I have an AVR. (It’s a 9.2 but for sake of confusion I’m calling it a 7.2).
How do you run surrounds? (no idea if that means speakers).
I want more" (no telling what or why)

I submit there will be no follow up.

If it is for movies only, an 7 channel amplifier should be fine.
If use it for stereo also, a stereo amp or 2 mono blocks + an 5 channel amplifier, featured with auto turn-on function is a plus.

how do you guys run the center channel surrounds and back surrounds. Another separate piece?

I use a Denon receiver as a processor, Sunfire Symphonic Reference Amplifier to power front left and right speakers and a 5 channel Sunfire Cinema Grand to power the center channel, side and back surrounds.

Normally, the main left/right channels are almost a requirement on processors.  This is because they are the "priority" channel.  If you have center channel or surround channels disabled, the processor will usually mix in those signals to the left/right main outputs.

If you do not have any front left/right speakers, I would still enable and use the left/right outputs of the processor and connect them to the "side surround" speakers.   Then take the normal surround outputs and connect them to the "rear surround" speakers.

It's not the best solution, but it will get you to where you want to go.