First we need some info on you. Age are you 10 or 40, sex, size, and have you ever shot a gun before. From the sounds of it that is a no or a limited time.

What you see with a screw in choke is a shotgun not a rifle. There is a diff. A shotgun shoots pellets and slugs a rifle has a metal casing with a metal normally lead or lead coated in copper. A shotgun say a 12ga is good for deer out to 100 max maybe more with a good scope and a good shooter. A rifle while it very if you have a 400 gun maybe 100 to 200 yards. 1500 gun with a good shooter maybe 500 yards.

Also what state are you in. Here in indiana you can not use a high power rifle.

If I was wanting to deer hunt I would go with the rifle. If I wanted to say rabbit hunt but also deer hunt I would go with a rifle and get a cheapo shotgun. You can get a mossberg 500 for 200 bucks that will do you for anything.
As for which rifle it depends are you in the hills of Ky or say Nc where short 100 yards or less in brush you might want a 30/30, if your in the plains out west then you might want the 30,06.

I started hunting at 19, I bought my first gun a 30 30 at a pawn shop and hunted on my own with no help(until I found this forum)

This is my 7th year and I have got close but no deer. You might do the education course to get the learning but it is also a good way to meet fellow hunters.

If your under 18 you might need an adult to go with.

Also come up with the answers to the questions I put out and a budget for a gun. you could spend $200 on a shotgun, 100 on a scope and $40 bucks on some slugs and shotshells and be good or you could spend $800 on a bolt action rifle, $400 on a scope and 2 bucks each for bullets.

Might look at a muzzleloader also mine is good out to 250 yard with my scope setup and allows me to hunt the gun and muzzleloader season which is twice the hunting time with my gun.