How do you buy new clothes on the Sims 3

On the Sims 3, what I do when I want more clothes is I go to my closet (where you buy from buy mode) and I click on my closet. Next, I click Plan outfit where you can design your own outfit and you don't even have to pay! Isn't that amazing? So that's what I do to buy clothes. If you want me to explain how to do it just ask, how do you design clothes on Sims 3.