Anyone know more on bitcoins then me that can explain some?

Basically, I made some topics on SourceOP and shits on selling TF2 keys, I cannot do paypal as they restrict me from having an account (being underage) and I feel like it's very risky to do it like that.

From what I found there's no age limit on owning bitcoins, and selling them for money (bank transfer) doesn't seem like that either, but I'm really confused in all this.

What site should I use to "sell" the bitcoins?

I live in Sweden, and I use Handelsbanken as my bank.

I suspect what I need to be paid in is through international "bank wire"?

Is everything automated on the site you just posted on? How does it work?
Do I just press a button and transfer my bitcoins to them, and provide my bank information and after a few days I get my money into my bank account?

ANY HELP IS HIGHLY APPRICIATED! I'm a bit stressed out right now.