Do some reading on Data Validation Lists and VLOOKUP.

Data Validation List Links:
http://office.microsoft.com/en-us/ex...005202215.aspx
http://www.contextures.com/xldataval01.html

VLOOKUP Links:
http://www.techonthenet.com/excel/formulas/vlookup.php
http://office.microsoft.com/en-us/ex...005209335.aspx
http://www.timeatlas.com/5_minute_ti...ookup_in_excel