memory card

I was trying to put some pics on the memory card for a digital pic frame , I put the card in the sd slot on my computer and opened it up ,there are already some pics on it and still lots of room for more , I was trying to drag and drop from other files but every time I tried it gave me an error message that says " connot create directory or file " if I remember correctly that is how I loaded the others, and how do I change pics from bitmap to jpeg ?

 

IrFan View can change from mp to jpg
http://www.irfanview.com/
File menu then batch conversion/rename