First off let me apologize for not having responded sooner.
Now on to the steps to get those maps working!
1) Find your Company of Heroes application
2) Right click on the icon and select "Show Package Contents"
3) You need to navigate / create the following path:
Contents/GameData/WW2/Data/Scenarios/MP/
NOTE: most of the path already exists, where it does not exist create a new folder.
4) Download the custom maps into the
MP folder.
5) Launch CoH and have fun
Additional Note: The seem to be a few ways to have custom maps made for CoH. You really can't tell which ones you are going to get until you download the zip file and extract it. After extracting the downloaded files, you want to copy into the
MP folder the files of the following types:
.scar
.tga
.info
.sgb
.xml
and any image file types.
Also if there is a
Loading Screen folder in the zip file and you want to be able to use it, create another folder in the
MP folder called
Loading Screen and copy the files into it (this doesn't always work).
You do not need the .sga or the .bak files, if the download only contained those files, I believe those were some sort of development file and not ready to be played.
Sites that I have found some good maps at:
http://companyofheroes.filefront.com
http://coh.gamebanana.com/maps
I hope you enjoy.
EDIT: Removal of an unneeded edit