Copy everything in the map folder except the following:
-All .osu files
-All .osb files
-All subfolders (eg SB)
Make a new folder under \skins and put them in.
Next, find a skin.ini from one of your favourite skin and copy into the new folder. Open the skin.ini and change the Name of the skin. You may want to customise the rest (eg circle colour, slider behaviour) in the skin.ini, have a read of the
skinning tutorial if needed, there's a whole section on skin.ini.