How to :: Add the custom maps
D:\Program Files\Steam\steamapps\common\left 4 dead 2\left4dead2\addons
^ this will be somewhat the directory path, though you will probably be under the C:\ drive, not D:\
Sometimes RAR files will contain more than the VPK file - usually there is a readme - READ IT, you may have to place some extra files into your l4d2 maps folder.

If you have questions regarding how to add maps and files, ask surmata or infested soul



Maps to acquire -

Custom L4d2 maps -

http://www.l4dmaps.com/details.php?file=5055 City 17

http://www.l4dmaps.com/details.php?file=4861 Death Aboard 2

http://www.l4dmaps.com/details.php?file=4457 Freezer Burn

http://www.l4dmaps.com/details.php?file=4517 Dead City 2

http://www.l4dmaps.com/details.php?file=6454 Heaven Can Wait 2

http://www.l4dmaps.com/file-download.php?file=6178&entry=13991 Indiana Jones


Original L4d Maps -

http://www.l4dmaps.com/details.php?file=5775 Dead Air Modified

http://www.l4dmaps.com/details.php?file=5772 Blood Harvest Modified

http://www.l4dmaps.com/details.php?file=5776 Death Toll Modified

http://www.l4dmaps.com/details.php?file=5777 No Mercy Modified