See the JkDefrag homepage, the FAQ (Frequently Asked Questions) chapter, the "How do I specify an option, or select a single disk (or folder or file)?" question.

thank you for the quick reply.
if i follow the FAQ correctly starting from the command line i should do the following " JkDefrag C: "

last night i down loaded the programme and found it great but it took ages to defrag my backup disc (which is unnecessary )how do i defrag only my "C" disc  :oops: