Which gym you go? You can always make friends and some will help you on bench.
Why you still ask for leg press exercise when you yourself already mention Squat?

I am lazy for isolate, so I always go for bench press, squat, pull up, hanging leg raise, etc..
You will surprise that it actually work out more muscle.

Anyway, welcome to body building world and hope you do learn and gain result in the future.
Perhaps make friends in your gym, and perhaps some will teach you the correct way.
Good luck!