Welcome! I grew up around guns but didn't get my first until I was in my late 20's and had to learn a few extra safety rules.
So, how do I go about becoming a responsible gun owner?
I can't speak to classes altho I would think you could ask at the gun range, local gun clubs (web search), maybe something NRA sponsored. I applaud you for thinking about this.
Also, learn the four safety rules. (
http://www.thefiringline.com/Misc/safetyrules.html) or (NRA rules here:
http://www.nrahq.org/education/guide.asp)
I'd ask the question re: using a class firearm vs. your own.
And what gun should I pick?
Usually the advice is -- shoot whatever gun you can shoot well.
Getting the right gun is a little tricky. You might want to try several (once you learn basics of how to shoot).
Some guns are harder to shoot than others. Guns with a lot of recoil are harder to shoot accurately and are a lot to deal with as a new shooter, I think.
Recoil comes from either because of a powerful cartridge, big bullet, or lighter guns or a combo thereof.
I think a 1911 would be harder to control than other guns. But you should try several out (maybe you're near a range that rents guns). I think .45 ACP may be a little much for a new shooter. You might go with .40 S&W or 9mm (cheap so you can afford to practice a lot). If you go with a smaller caliber (.380, 9x18 Mak, .32 ACP, etc) it may come in a small enough gun that you get a lot of kick.
I think your best bet in terms of recoil and price is 9mm. I have been shooting 115g UMC ammo which I found to be fairly light recoil in the gun I'm using. You can work your way up to the heavier weight bullets and hotter factory loads later.
I would get a full size / full steel gun to reduce recoil.
Michael