Mods are located within the 'mods' folder inside of your MW2 folder. Each mod has it's own sub folder inside of the /mods folder. The name of that folder is how ♥♥♥♥ identifies each mod and it also determines the name that you will see in the mods menu inside of ♥♥♥♥.

Call of Duty Modern Warfare 2/mods/bots
Call of Duty Modern Warfare 2/mods/PropHunt

Once you have a mod downloaded you simply move the folder of the mod into the mods folder. Then select the mod in the main menu and then the game will reboot with it loaded.

Example of mod:
Call of Duty Modern Warfare 2/mods/bots/z_svr_bots.iwd

The mod will show up in the menu as "bots"

You can check out the endorsed mods listed here:
http://steamcommunity.com/groups/♥♥♥♥/discussions/0/1470841715964462535/
Or a google search will get you plenty of mods.