Look for the size in cm somewhere on your bike. If it's small it'll be between 50 and 53cm.
You've probably got too much weight resting on your hands. Try raising the bars slightly. Could be as easy as flipping your stem over, and tilting your bars slightly upwards.
Bike bibs. Decent pair.
(Shorts give you muffin tops and cut into your waist, they suck)
Bike saddle is tricky. Find a shop that has demo saddles and play with different widths and shapes. Hard/soft, wide/narrow, flat/curved. I went through around 6 different seats before I found one that doesn't feel like I'm about to be sterilized after a few hours.
Conditioning helps. Day 1 ride, you'll be fine until the tail end of a ride. Day 2 - you'll be sore, but try to get out for an hour. Day 3 - pain should subside. If you still have pain or numbness then the seat is wrong. Change it up.
Also try lowering the seat a bit to even out your position. Easy way would be to lower it to the point where you can barely touch the ground while sitting on it. You should also be able to move your heel through the full pedal stroke. "Scraping the pan" with your heel.
These are cheap solutions, but without knowing height, weight, knee situation, ankle situation, etc, there could be more at play. Getting a proper fitting would be the next step. Expensive, but keep the measurements and you'll be able to transfer that setup bike to bike later on in life.