Several ways to realize this:
1. Putting those values in the definition of the field in the table.
2. Linking to another table in the definition of the field in the table.
3. Putting those values in the definition of the field on the form.
4. Putting those values in a separate table and linking to that in the definition of the field in the form.

By the way, such a field it's called a combobox (at least in older versions of Access, not a "drop down menu". Once you know that it's easy to find whereever you like (help, tutorials on office.microsoft.com or elsewhere on the Internet).

#3 and #4 are nicely illustrated (although for older versions of MS Access, so details might be different in 2010) in http://www.techonthenet.com/access/tutorials/combobasics/basics01.php

#1 and #2 see http://www.brainbell.com/tutorials/ms-office/Access_2003/Creating_A_Lookup_Field.htm (also tells about #1a).

Kees