Last Updated- 8-8-2012 Click on photo to enlarge Firstly, to be on the safe side, please hash the file, this is purely up to you, this just verifies the file you have downloaded hasn’t been tampered with. Right click the zip/rar file-goto properties Next goto the -File Hashes-Tab, copy and paste the MD5 hash off the website and paste it into the Hash Comparison box. If you have a tick, then all is correct. Next we need to unzip/rar the file by using 7-zip, just right click the zipped file then 7-zip and Extract here. Make sure you are In the add-ons  folder when you unzip the file. C:\ProgramFiles\Steam\steamapps\ common\left 4 dead 2\left4dead2\addons Click on photo to enlarge Click on photo to enlarge Next, double click the .vpk file and you should get a popup saying it successfully Installed. Close Left4Dead2 and restart it, your addon should be now Installed and available to play. Make sure you have addon support enabled in left4dead2. Click on photo to enlarge Download 7-Zip If you don’t have winrar or winzip Download HashTab to verify the file you are downloading