ALL OF THE ABOVE!!!
4 months ago Valve announced this feature and said it's coming 'soon'... You can expect it next year.
And about your comment:
This is the program they used to make the game. So basically they're giving you all the tools you need to make a full game, and even try to compete with Valve's work. And believe me, the thought you can make something better haunts them every day.
I can't really add much to this topic but remind you that the learning curve isn't so much of a curve as a wall. Just be glad that you aren't starting off with Portal 1 like I did. 
Just getting a single button set up was a nightmare. (for a beginner, that is)
The problem with a really simple map editor, such as in the Sims, is that you really don't have much control. I'm thinking back to po_edit, which looked cool but there really wasn't much you could do. There's no way you'll be able to do much of anything you see in current custom maps with just copying and pasting.
Another thing to remember is that even when you've "mastered" (sort of) the tools it's by no means a fast process. Most decent map packs take longer than 3 months or so.
Just keep trying, and we're here to answer any questions you may have about getting started, though remember to check the VDC and search the forum before you make a new post.
And if you're looking for tutorials, I've got a few basic-level tutorials on my website. The link is in my signature. (TBH, they're probably lower quality than what has already been posted here, but they're still there.)
[spoiler]WOM Test 1
Laser Cube Quest
Mho' Power - Community Spotlight!
Four Corners[/spoiler]
NEXT YEAR!??!?! i was hoping in, like, a month.
well i better start working
well i better start working
It was a joke about Valve Time: https://developer.valvesoftware.com/wiki/Valve_Time
[spoiler]WOM Test 1
Laser Cube Quest
Mho' Power - Community Spotlight!
Four Corners[/spoiler]