If the FP database handles SQL the way other databases do you should perform a select in this fashion:
SELECT * FROM tblAddress WHERE [Name] LIKE 'varName'
The % is a wildcard character to allow you to get results where the varName matches a portion of the table field.
For instance, if you have a field in your table called "Name" and one of the records with the field "Name" has the contents of "Gregory" and another record has "Greg" you can perform a select statement to pull both of these records using the % wildcard character in this way:
... WHERE [Name] LIKE 'Greg%'
This condition will pull all records that meet the criteria of having the first four letters of 'Greg' in the field [Name].
You will have to be careful with some databases as they are case sensitive. So 'GREG' and 'Greg' are not the same. You can alleviate this problem with a function called UPPER (may or may not be supported on the FP database).
Select * from <tablename> where upper(Name) like(upper('varName'))
This statement will cast the field "Name" and the varName to upper case in order compare apples to apples.
As for your select statement, the '%%%varName%%%' will retrieve all records that contain varName within the field. This is because you specified the % on both sides of the input host variable.