1-. How can i sell fast my map?
just post a video of your map, and tell them you are selling it
2-. In which page i make my account to recive the money?
www.paypal.com
3-. How to trade?
the buyer transfers the money to your paypal (or other) account, and then you sent the map, there is no official MTA Map trading system
4-. What is the most important thing in a map, the deco or the track,( or both)?
these days good decoration is very important, but the track is very important as well ofc, so both