There are two basic ways of adding smileys sets.
One way, is to add them as a modification (Package).
If you search the mod site, you'll find loads of them!
http://custom.simplemachines.org/mods/index.php?action=search;type=12
But, be aware that installing those MIGHT bring problems, which are described in the note, at the end of this section.
The other way, is for you to create a directory, inside your forum's "Smileys" directory, giving it the name that you want.
Then, upload all the actual graphic files, for your smileys, into that directory.
That having been done, you can go to Admin>Smileys and Message Icons>Smiley Sets and click on... Wait for it... "New smiley Set"!
When you do that, the first thing you'll notice is that you need to give your new smiley set a name. I'd suggest that the logical thing to do, is to give it the same name as the directory you created.
Now, when you click "New smiley set", you'll see "URL:" and, to the right of it, a requester.
Use that selector to select the set's name, that you made, earlier.
Check the box labeled "Import smileys already in this directory:" and, if you want to make this set your forum's default set, check the box labeled "Default smiley set:".
When you click "Save changes", your new smiley set should be recognized and installed.
NOTE:
If you have more than one smiley set, it's advisable to make sure that all sets contain graphics files with exactly the same names in all sets.
The reason for this, is obvious, when you think about it.
If two of your members are using two different sets of smileys, they won't see each-others, if the files do not have the same names! Or, if one image appears in one set, but not the other, they'll just see weirdness.
This is all you can do on this page. If you want to add smileys to a set, edit their code, placement order, places they are displayed (ex. On Post screen, pop-up or hidden) you need to enable Enable customized smileys on the Settings page of the smiley section.
