Copy the graphics, sounds, and the data somewhere and use an archiving app (such as WinRAR or 7zip) to pack it all up.
In order to make it easy to extract, the contents of the archive file (.zip, .rar, .7z) should be ordered like thus:
----your mod folder\
------your data files
----your sounds folder\
------your sound files
----your graphics folder\
------your graphic files
If you don't use any new/modified graphics or sounds, you can leave those folders out of the archive file.
After you've got the archive file, go to <!-- m --><a class="postlink" href="http://www.mediafire.com/">http://www.mediafire.com/</a><!-- m --> or some other file hosting place and upload it there. You'll then need to post the link provided by the file hosting service.
Or, alternatively ('though I'm not sure what sort of size limit there is, if any), you can click on the "Upload attachment" tab right below the "Save", "Preview", and "Submit" buttons, click "Browse..." to find the archive file, and finally click "Add the file" to upload it as an attachment, which people can then download (you need to press Submit after uploading the file).