In order to extract DNA from sperm cells you need the same method as the extraction of DNA from body cells, for example the Qiamp method from Qiagen.
The DNA in sperm cells will show a complete DNA-profile from the person this sperm is from (the same profile as for example from that person's blood or saliva). If you would be able to use only one sperm cell for DNA profiling you would see only half a profile (because each sperm cell contains only half of the genetic profile of the person it comes from).
Another DNA-test that can be used with sperm is the amplification of Y-chromosomal markers on the Y-chromosome in these cells. These markers will be the same throughout all males in a pedigree with the same father, grandfather,etc. There are some websites regarding this subject such as:
