It would really be helpful to know WHICH county you're in - I'm going to assume Otsego, since wikipedia says so...
Assuming you have a valid ID on the wiki, all you need to do is to bring up this article..
Otsego County Michigan - the RR Wiki
Go down to the Fire/EMS tone out section and click on the 'EDIT' link on the upper right of the section header. Add your data in between the div and /div tags, then save it (there's a button on the bottom of the edit form -you can use preview to see if the data will come out the way you intend to, but keep in mind your changes are NOT saved until you tell it to). You're done.
If you find you can't sign onto the wiki, send Lindsay a note. The admins don't have access to those servers. HTH Mike