Sims won't change clothing

Is there any one out there that can help me with my problem?  once the oblects have been downloaded into Sims Mod  how do I get them into the game so my Sims don't have to wear the same thing day after day.  The clothes are in the mod file but I go to play the game and I can't find the new clothes I downloaded for her.  In Sims 2 I could go shopping for the clothes at the mall and once I purchased the clothes and took her back home the new clothes were in the wardrobe.  I could not find a place to go shopping for her in travel.  I hop someone understands what I am asking and can help me with this  Thanks