The various items under Group are the object's components. You can indeed map them separately (create a new map for each) but you can also create new groups by selecting some items ,'create a new group' then map the group. You should check the tutorials at uvmapper.com for a step by step explanation. The tricky part, I guess , will be to identify with item is what in the original object. Creating the texture mapping isn't that difficult, but can take some time depending on the object's complexity.