External expansion drive on my computer?

i bought this expansion drive (g) to save music, pictures and videos on it because my computers memory is full. I have saved some pictures some how on here, but they are old pictures. But the problem is, my computer only saved about half of them on there. Is there anyway i could go into G and delete these half then move all of the picture and ect on the computer. I dont want these files on my computer at all, i want them all on the expansion drive: but i'm afraid something might happen that will erase all of the files before i put them on G.