Mapping is a daunting thing. I've worked on a CS:S map for over 4 months now and it's still not done. I'm guessing that you've played through HL2 or CS:S and really want to make some of the things that they've done, but you're going to find it difficult to do something as complex as VALVE's or Turtle Rock's work.
Start simple. Make a room, rather than an outdoor thing. Outdoor maps are a lot harder to do for a beginner, and you're gonna struggle, as the screenie indicates. Take a look at the Beginner tutorials on the site: they may be for HL1, but they still work. Don't expect anything brilliant to arrise out of your first maps: they're gonna suck. Nearly everyone's first map totally sucks.
"OMFGZORSTHISSUXBALLSLOLBADBRUSHESFORFUCK
SSAKELOLOLOLLOLOL!!!"
If you can't take constructive criticism as demonstrated by Kasperg (who is one the sites best mappers) then you're gonna find it very hard to become a good mapper. Exaggerating what Kasperg said into something that doesn't even resemble what he initially said is childish.