How do you get write permissions for an external uSD card?

I'm trying to add music to my Sansa Sandisk Clip+ player, and I have a 16 GB micro SD card in it. When I try adding music to the SD card though, it says I don't have write permissions. The properties don't give me a security tab or anything to change it, I don't know how to get write permissions.|||Your card is messed up you can try to formatte it, but if you can't even get that done through admin, control prompt then the card is garbage. Did you use the card in a previous device? I had an 8 gig in a LG Andriod phone and it did the same thing.