Have some troubles
 

i'm using read hat 8.0
When i typed rpm --rebuild pr rpmbuild --rebuild to make rpm for my machine for source rpm,rh 8.0 said "the command're not found"

Well you should give a source rpm package name with that command so it will know what to rebuild. But if it says command not found then it's either not installed or not in your path. Since redhat is a rpm based distro I highly doubt it's not installed. So most likely you should find out where it is installed and add that location to your path. Some commands which could help you find it's location:

which rpm
whereis rpm
locate rpm

And if you are wondering how to modify your path then I suggest searching the site first, since there are many threads about how to get that done.