I would repeat my same old recommendation that I give everyone here, which is to read a book on CG basics before playing with software, but it just makes everyone real angry, so I won’t.
Instead I’ll give my 10 minute version of UV mapping. Of course there are a billion tutorials out there on the internet if you want to search.
My best analogy for UV mapping is this:
If your mom ever did any sewing and you saw what she was doing, you know something about it. She went to the store, bought a “pattern”, then bought some fabric, laid the pattern over the fabric on a flat “2D” table, cut out the pieces, and sewed them together (at the seams). And when all the pieces were sewn together, it fit on your 3D body.
UV mapping is the reverse, where you take your 3D body and make a flat, 2D pattern.
Now, go to your closet and grab a pair of pants. Look at them. Look at where the seams are. There’s a seam down the right side, one down the left side, and one along the inside of the legs and thru the crotch. Pretty much just three seams to make two pieces of fabric fit on your 3D body.
It’s exactly the same thing with UV mapping, except you’re trying to apply a 2D texture image to a 3D object. If you were going to apply a texture to a pair of pants for your 3D character, you’d make the same seams that are in a real pair of pants. The fabric is the texture you want to apply.
It’s almost as if someone had spray painted a pair of pants on you, and the paint turned into fabric, and you had to figure out how to cut the fabric into the fewest number of flat pieces. That’s why it’s called “unwrapping”.
You are basically trying to figure out how to take a 2D texture and apply it to a 3D character. And the best way to do that is use the same techniques that clothing makers have been using for centuries.
Right now focus on seams. Pins are useful sometimes, but you first need to really grasp the concept of seams.