- using a pre-compiled package (easier)
- using a slackbuild script (easy)
- using sources (less easy)
Understanding how and where software files are stored
Usually in Slackware software is installed in /usr/, unless you specify otherwise. In most cases you will have all the software's files copied to /usr/lib/softwarename and a symlink in /usr/bin, usually linking the main executable placed in /usr/lib/softwarename.