That would make things a lot easier if we could see the names of the clothes in our wardrobe, either on the page or when we move the mouse over the picture of each cloth.
If you still haven't figured out - as you posted that a very long time ago - the outfit you need to wear, probably you haven't tried all the combinations in your wardrobe, or you simply haven't bought the right parts from the shop yet.
The sport ensemble Sasha wants you to wear includes :
- the top #4 at the girl's shop, shown as a long sleeved red top with a zipper and yellow wrists,
- the bottom #1, shown as red pants.