calinminet, I'm moving this to its own thread as the one you posted in was close to 2 years old. Your best bet to start editing your store is here:
http://forum.x-cart.com/showthread.php?t=21529
That will help you edit colors, and give you a good base for editing layout as well.
As for editing text in your store, there are two methods:
1. Webmaster mode (covered in the thread I linked above as well as the manual)
2. Your 'Languages' area
I know it is not fun to be told to 'read the manual', but in some cases that is the best approach, as explaining it all over and over just isn't a good use of anyone's time. Look for 'Languages' in the manual as well as "Webmaster Mode".
I hope you find this helpful.