1. Create a new text field gSearch, set storage to global and place on layout. Under the inspector select Dropdown List.
2. For Values From: click the pencil and make a new value list. Call it Meter Location Search. Under Edit Value List, select "Use Values from Field" and for the field select your Meter Location.
3. Create a new script with the following script steps:
a) Enter Find Mode (uncheck pause-no parameters)
b) Set Field [YourTableName::Meter Location; gSearch]
c) Perform Find  (no parameters)
4. Attach a script trigger to the gSearch field. Select OnObjectModify. Select the new script.
That should do it.
Edit: fixed script
I would also add that you should have a look at the starter solutions.
When I started with Filemaker, I was in a similar boat as you, with the added bonus of having no experience with any database software. Looking at the starter solutions really helped me, showing me what can be done with filemaker and how to do it.