Hey there ViperSS, welcome!
If you haven't already, check out UEAKCrash's tutorials on the YouTubes. They're so good even Valve took notice of them and made a blog post about it! Check those out
here.
If you want to make mapping for TF2 a bazillion times easier, download and install the
ABS Resource pack. It's awesome and brilliant and super easy to install and work with.
For other stuff join the
discussion and question section here to ask anything about everything Hammer/TF2/Source related. If you have any maps you want to show to the world and get tested, upload them
here by clicking on the big blue button on the top right that says "Add Download". It gets put in the
Map Factory automatically for you, which is the place to use when you have an update to your map. Once you have your map uploaded, you can put them in a gameday (announced
here) to get them tested, or ask people in the
TF2maps Steam chat to play the map on an impromptu test. If there’s enough interest (which there usually is) you’ll have your map tested by a bunch of the finest mappers around.
The
Valve Developer Wiki is also a great place to search for things related to Hammer and Source, as well as other Valve titles you might want to map for. Finally, there's
this place. If after compiling something is broken, or if there's something in the compile log you don't understand, run it trough the website to have it check for errors. 90% of the time it points you to the error, and it saves you from having to post your compile log here (which we're gonna run trough the same website anyway since we're not libraries with every error in our brain). If neither you nor Interlopers can figure it out, post it here anyway. That part about us not having every error programmed into our head isn't entirely true by the way; some of us do have it in their head.
Have fun with Hammer! Just don't forget to mash CTRL+S after every change you've made in Hammer, just to be sure.
Have a great time here, and most importantly, have fun! (that's so important I have to say it twice within 3 sentences!)