You can do this a couple of ways.
One is to add criteria to the underlying recordset and on the AfterUpdate event of the textbox and requery the form, limiting the recordset to one record
Another is to use a VBA recordset to find the appropriate record and display that.
If you use the search facility here, you will find a lot of answers and even Db samples of search facilities within a Db. If you cannot find what you need, get back.