what you must to to install an app for a mac computer is this.
1. go to a folder on forums and click on something you like.
2. dowload it and then get off safari and onto your desktop.
3. open up a folder on desktop and search for downloads
4. drag and drop the addon(s) from the folder onto the desktop
5. open up the BL folder(not BL, but the folder)
6. then drag the addon(s) form the desktop in to the addon folder inside the BL folder
7. start up BL and go to start a game
8. go to addons above where you put server name
9. scrol down untill you see the addon in there, than chack it and start the game and there you have it.
