Creating a Function

Here's my scenario:
I am creating documents on multiple worksheets in a workbook. Info on the documents will be changed for each client then the workbook will be "saved as" for each client (maybe I should have made the original docs as templates?). My problem right now is that one of the docs is Terms and Conditions for a Caterer. The last page of the doc needs to have the caterer's name, address, phone, fax, email and website info inserted. The person filling out the doc will have to choose from a list of 10 caterers. Instead of manually entering that info each time, I thought it would be easier to have one of the worksheets be some kind of database of all the caterers, so that a simple keystroke in the cell on the doc would call up the caterer's info from the database. I am not experienced in macros or arrays etc., so if you can help me, I need instructions in layman's terms. Thanks in advance.
--Kim