inserting the link to seconf

In the first table there is a link to a second table .
Creating a new record in the first table I need to insert the key of the wanted record of the second table into the link-field. I will use a form application.

When I am adding a new record in the first table, how can I search for a record in the second table that contains field(s) I know (e.g. first_name and last_name ), and get back the key of the wanted record of the second table?

Title should read: Inserting the link to second table

Hi sawjer
How about a capture link to a grid representing the records from second table?