The sense of pôr used here is most likely intended to be:
- Usar uma peça de vestuário ou de calçado. = CALÇAR, VESTIR
As you can see in that source pôr has many meanings, but given that we're talking about a garment and that there is no other context, I think that if you meant any of the others, you would use a more specific verb or phrase.
I do not know how to explain the full gramatical implications, but in English, you do not finish the sentence with a preposition. In my opinion, the more correct phrase in english should be "She wants to pun on the skirt." This is just an opinion, so please correct me if it is wrong - we are all learning.