What's up with downloading maps now?
The PTI maps are the ones that the thumbnail looks like a draw of a test chamber. Not all off them are bad, but most of them are really a waste of time because anyone can create anything and upload it, so they just spread some test elements in a room, connect them, add some goo, some turrets, and there it is. Some of the users even use mods that easily allow them to add some custom features. You can pick the maps that are best rated, they normally have more information, and there's also a lot of them. 5 stars, 4 stars, there are even some 3 stars that are worth having a look 
Thanks for the help guys, I do appreciate it. So after I buy the game on steam, the maps I subscribe to will automatically get downloaded when I launch Portal 2 from steam? Is that how it works?
The maps will get downloaded the moment you subscribe to it, so when you open the game, they'll be ready for you to play
Thank's again Pedro. You've been very helpful.
Also keep in mind those "mappers" who export from PTI into hammer. At first, it probably doesn't sound like a bad idea, but it gives you a bunch of stupid cubes and overly-complex puzzle elements. These maps are harder to avoid, so look out for them. If you want hammer only maps, check the box in the workshop that says 'custom story'. Most of these maps will be entirely made in hammer and tend to be a Lott better overall.
Musical website Moddb
Sometimes that can be a good thing though 
you don't have to remake the whole test for one, which is a godsend on complex chambers. First thing I do when I import maps into hammer is fix all of the asinine brushwork. Takes forever but so worth it. Next up is trying to fix the "giant Lego set" aesthetic. Which is harder. Whatevs.
But yeah, most PTI to Hammer maps are by people who looked up 1 tutorial on YouTube and think they know everything *ever* about mapping. That *always* ends up with a grade-A shitmap. Most of the time they can't even design a good puzzle, lol.
Anyway, more on topic - you'll love the PTI. You can't really do all that much and the puzzles have a rather cookie-cutter look&feel, but nonetheless it's a great tool for whipping up puzzles. Top Rated All on the workshop is a good place to start, if you scroll past Designed for Danger and 12 Angry Tests. You might want to get your hands on maps by Mevious, josepezdj, cyhborg, greykarel, eMbAh, and anyone else who yells at me for not including them in this list if you want a headache.
Sometimes that can be a good thing though you don't have to remake the whole test for one, which is a godsend on complex chambers. First thing I do when I import maps into hammer is fix all of the asinine brushwork. Takes forever but so worth it. Next up is trying to fix the "giant Lego set" aesthetic. Which is harder. Whatevs.
But yeah, most PTI to Hammer maps are by people who looked up 1 tutorial on YouTube and think they know everything *ever* about mapping. That *always* ends up with a grade-A shitmap. Most of the time they can't even design a good puzzle, lol.
Anyway, more on topic - you'll love the PTI. You can't really do all that much and the puzzles have a rather cookie-cutter look&feel, but nonetheless it's a great tool for whipping up puzzles. Top Rated All on the workshop is a good place to start, if you scroll past Designed for Danger and 12 Angry Tests. You might want to get your hands on maps by Mevious, josepezdj, cyhborg, greykarel, eMbAh, and anyone else who yells at me for not including them in this list if you want a headache.
Thanks again guys for all the tips. I'm freaking addicted to this game. I bought it on steam and have logged over 40 hours already lol