look up formula

look up formula

I need to some how set a field so that when a store # (i.e 11193) is chosen from the drop down list, it's populates the district # ( i.e. 222) automatically in the proceeding field.
 
I am not in any way good w/ formulas and need help pulling this info from an excel spreadsheet. and please don't tell me to refer to the help guide like the person on the phone did. :)
 
Thanks!!!
-Melissa