We have an old Linux server that nobody on-site knows anything about. It's Tao Linux... pretty sure that's Redhat-based. Anyhow we ran into an issue that appears to have been a bug in our version of Samba. So we DL'd and installed the newest version from samba.org. Now we have two versions installed, but the old version is running. How do we make it run the new version? Keep in mind - I'll need pretty specific instructions. Complete Linux noob here. Thanks!

The samba daemons nmbd and smbd are typically in /usr/sbin/. If you installed from source hopefully the new version was copied /usr/sbin. So try restarting and see what happens. If this does not work then we need to see the steps you took to compile and install.
service smb restart