The enclosed "UMOD Installer" lets you install "mods" or add-ons to Unreal that you dowload from the Internet. If you download a file that has a name ending in ".umod", then you will use the UMOD installer to unpack and install it in your Unreal folder.
To start, copy the "UMOD Installer" and "Manifest.ini" into your Unreal folder. You may also want to open the "System" folder inside your Unreal folder and throw away the existing "Manifest.ini" file that is already in there. Throwing away the extra manifest file shouldn't be necessary but keeps things tidy.
Now, go grab your favorite Unreal mod from the web (a good starting place to find maps and mods is http://www.planetunreal.com/). When you download a umod file, if it is zipped, make sure that when Stuffit or Zipit uncompresses the file it does not try to use the "Convert text files to Mac format" option from the Stuffit/Zipit preferences. If the umod file is thought to be text (which it is not), and converted, it will not install!
Once you have downloaded the umod file, simply drag it onto the "UMOD Installer" application in your Unreal folder and follow the instructions. After you install a UMOD, you will probably see a new .ini file in your Unreal folder, don't throw it away! You will also probably have instructions for the mod installed in the "Help" folder in the Unreal folder. Simply open the appropriate readme file (usually an HTML file for your browser) to find out more about playing the mod.
