Instructions
Download a mod for "Battlefield 2." Since these mods are created by the game's community, they are typically hosted across a variety of file-hosting and fan-created websites for the game, such as FileFront, Strategy Informer or Planet Battlefield. Once downloaded, the mod will more than likely be a compressed folder.
Extract the downloaded files with a file-extraction program, such as WinZip, WinRAR or ExtractNow. To do this, right-click on the folder, click the "Extract" option then choose where you want the extracted folder to go.
Move the extracted mod files to the game's "Mods" folder. This folder is located in the game's directory, which is wherever you instructed the game to be installed. By default, the folder's file path is "ProgramFiles\EAGames\Battlefield2\Mods." Depending on the mod you downloaded, it may have an executable (.exe) file with it. If not, your process is complete, and the mod will be loaded the next time you start the game. If an .exe file is included in the extracted files, proceed to Step 4.
Right-click on the file, hover over "Send to" then click on "Desktop (create shortcut)." A shortcut of the file will be placed on your desktop. Double-click on the shortcut to start the game with the mod activated.