nope you're english is just fine
start with a clean unzipped xlobby folder
then unzip the stuff from the XLobbyMC download and put the stuff from databases into xlobby\databases and so on for each folder
so the skin should be located at
Xlobby\skins\XLobbyMC-720x480\lots of files and folders
ACTUALLY...since your'e new to xlobby try just extracting the skin zip file directly to the xlobby folder and letting it overwrite the old file
then start XLobby
press F2 and goto the 'Skins' tab...choose XLobbyMC in the drop down box and press restart
let me know if that gets the skin showing for you