Thank you for your post.
This is not an easy task for a new user to be completed by Tuesday!
However, this may help you.
In your database file with the 200 dealer records, perform the following steps:
1. Pull down the View menu and select "Layout Mode". This will take you to how you want your fields presented.
2. Pull down the Layouts menu and select New Layout/Report.
3. Select "Blank Layout".
4. You now have a blank screen. Either create a drawing for the different regions, or create some text boxes and enter the different regions.
5. Pull down the Scripts menu and select "Manage Scripts"/
6. In the bottom left corner, click on the icon that shows "New" with a green plus sign.
7. At the top for Script name, enter "Northwest" or a territory that makes sense.
8. On the left side of the screen are commands. Select "Enter Find Mode", and it will now appear on the right side. Uncheck "Pause".
9. On the left side, double-click "Set Field". Specify the target field as your region field. Click the lower "Specify..." button and enter "Northwest" (with the quotes) and click OK.
10. On the left side, double-click "Perform Find" (not Perform Find/Replace... look lower).
11. Your script should now look like:
Enter Find Mode 
Set Field [ Region ; "Northwest" ]
Perform Find 
12. Close this window and save the changes.
13. Go back to your layout, click on the box that has "Northwest" (or the region you want to specify). Pull down the Format menu and select "Button Setup..."
14. Select "Perform Script", and on the right side, click "Specify" and select "Northwest". Click OK.
15. Pull down the View menu and select "Browse Mode". Click the Northwest button, and FileMaker Pro will only show those records.
Repeat the above steps for each of the buttons.
To share this on the web, pull down the File menu and select "Sharing -> Instant Web Publishing...". Turn on Instant Web Publishing, and write down the IP address. Click your dealer file in the lower left corner, and on the right side, set access to "All users".
Go to another machine, launch a browser and enter:
http://<IP address of other machine>
You can now select the file, click the button, and only those dealers will be seen for that region.
This should give you a good starting point. If you run into any difficulty, please let me know.