if my 1997 chevy suburban wont crank when I turn the ignition what can I do.

Sometimes people install a new starter for an older chevy. The bendix on the one in your vehicle should have the large stud for power from the starter/power out to your vehicle. The power terminal bolted to it to run the starter motor. There should only be one small stud where your ignition/crank lead goes. If you have two small terminals try switching the leads. On the older GM's they didn't power the engine from the ignition during crank, the power was routed to the distributor via the second terminal on the starter. All new vehicles have the engine powered through the ignition while in run and crank.

If you could get a cheap 12 volt light tester or cheap multimeter you could do some simple voltage checks and pin point the issue. Do you have power to the cab?

Just remembered. That is a Vortec right, will assume with an automatic tranny. They have a shift cable instead if the mechanical linkage. There is a shift position switch on the gear selector on the side of the tranny. These get worn out and fail. Try puttin it in reverse with the key on. If the reverse lights work try putting the unit in neutral and starting. Then try starting in all gears. The switch should let it start in either P or N. If it starts in N the park contact is damaged. If it starts in other gears you may just need to rotate the unit and remount, the mounting holes are slotted for this reason. If this fails go back to the key/ignition and test circuits.