how do u add thing into a set?

You cut it, paste it and stretch it and put in in the place. And then you save it 1x1 in jpeg or png or tga depending on your very own needs. If u need, the templaters are just over there in the shop/.

First you need to buy a set for 10 tc. Then in your inventory, you tick all the items you want to put into the set. Then click where it says -SELECT- and a drop down tab will appear.
Click which set to add the items to and then click submit.

you can also purchase sets from market wich is cheaper., and solax is right if you want to change the name of a set click on edit, then edit the set name and click update, not the numbers part the part from the name.