Shermanfreak has a good point: Info about modeling events should go in the Events area of the site because that's what we use as the basis for the Coming Events section in the magazine. You can enter info there as early as you want; if you're club's just had it's annual show, and you already know when and where next year's will be held (and all the contact info, etc.), you can add it to the Events calendar NOW.
If you want to draw extra attention to your event for the benefit of site members who may not always check the Events calendar, I suppose you post a message in the Community Announcements forum containing a link to your Events listing. (But keep all the detailed info in the calendar listing.) Something like:
"Subject: Model show in Waukesha, WI
Message: The FineScale Plasticworkers will hold their annual model show and pig roast on xxxxxxxx. Check out our listing in the Events calendar (url here)."