To install programs use as Ztyx suggests, rpm (for .rpm packages)

If you install programs such as Netscape that let you decide where you want to install it, you can use the directory /opt or /usr/local (<--default in many cases). To uninstall, there are many ways... depending how did you installed. For rpm packages it would be using rpm, for source tarball you can do a #make uninstall (if the program installed supports that feature in the makefile)

Again for mor info, read the rpm man page and the HOW-TO's, and for source tarballs, well... just ask.