Well, you're in the right place. But, as the people above have said, you need to practice on your own using tutorials and specific forum requests to get better. I have a graveyard filled with countless failed/incomplete test maps from past mapping sessions, and you will too. I guarrantee you that if you keep testing things and look at TONS of tutorials, you'll generally find out what you need to know to do the neat things you're dreaming of. Here's the biggest tip I can give: picture your dream map in your mind. Now, lock it away in a box and throw the key into a very dark place, because it is FOLLY to attempt your craziest/most complex ideas in mapping with just a handful of experience. In other words, DON'T try making your dream map until MUCH, MUCH LATER, after you have the knowledge necessary. Heck, I'm still in the planning stages of my castle, and I've been wanting to build that since I started mapping three years ago (Sadly, HL1's Hammer virtually died trying to process my first attempts).
Keep it up, I know you'll be doing great work sooner than you think!