Each Sally release lists its new features and fixes in its release notes. The full history, newest first, is on the Sally website:
Use Help/Check For New Versions to find out whether a newer release is available; Install and Restart in the update window installs it, and Sally also checks by itself (Configuration/General, Check for updates). A release you downloaded yourself installs with utils\salupdate.exe (drop the .zip onto it). See Installing and Updating Sally.
Sally continues Open Salamander, the open-source release of Altap Salamander 4.0. The release history of those versions is part of the Open Salamander sources.