Assuming you live in the US, as far as I know, to legally purchase a gun from an individual still requires a federally licensed firearms dealer to run a background check on the purchaser. The dealer acts as a middle man and charges a fee.
I have multiple guns of all kinds, all purchased from local dealers. The first was to CTB with but I fell in love with them and started a collection. It was easy. I just went to the store and said I wanted a handgun for personal defense, that I had very little experience and would they help me choose. A little nervousness is normal. If you tell them you are a newbie to guns, they will show you how to check it, in fact, they will do it before handing it to you. It is easy.
Personally, I would not meet anybody in a dark parking lot to buy a gun that may not even work. You don't know how to handle one safely, is it loaded, so many questions that the seller may take full advantage of your lack of knowledge which will be patently obvious. And it probably won't come with a handbook, which tells you everything you need to know. Also, the legal ramifications, if caught, would prevent any future legal purchases.
The difficulty now is to find ammunition. You can get it online if you look hard and act quickly.
Can you pass the background check?