Hi Ethel, bear with me I am pretty slow with this kind of thing but I assume I look at what it reads under "disk defragmentger". This says space 44%, 33.24GB with a capacity of 74.54.
Defragmentation is a pretty unexciting process, and you won't see things wizzing about. It sounds like you have ample space - if you hadn't XP would advise you.
Start it as you go to bed and leave it running overnight.
I always think the Analyse option is a waste of time, just go the whole hog.