1) Install Wolfenstein: Enemy Territory by double-clicking "Wolf_ET.exe"
2) Install 2.60 patch by double-clicking "Enemy Territory 2.60 patch.exe"
3) Install 2.60b patch - follow the readme found in the included subfolder
"Enemy Territory 2.60b patch"
4) Don't forget to check out Tremulous, Wolfenstein: Enemy Territory, Fighter Squadron: the Screamin' Demons Over Europe, FreeSpace 2 SCP (Includes the BattleStar Galactica, The Babylon Project, and Wing Commander Saga TC mods), and also, kkrieger, which is an interesting little booger.