I have two Excel worksheets:

Worksheet #1. - it has extensive information on customers, a fragment
of it is shown below:

Cust # Customer Name Country Region
EL017 A&A Comercial S.A. Ecuador CA
JA031 Kichi Tol Co Japan AP
IT014 A. Nardu, S.R.L. Italy EU

Worksheet #2. - is to be filled out:

INV# CUST# CUSTOMER NAME COUNTRY REGION
75836A JA031 Kichi Tol Co Japan AP
75870AX CR012 Invot S.A. Costa Rica CA

INV# - is a column with Invoice numbers to be filled out from a paper
file

CUST# , CUSTOMER NAME, COUNTRY, REGION - are columns to be filled out
automatically based on the information in worksheet #1.

How can I relate 2 sheets so that when I put into worksheet#2
customer's number (from worksheet#1) cells next to it will be filled
out with "customer name" , "country", "region information",
etc. ??

I created a dropdown menu in worksheet #1 in customer# so I can chose
the customer number but when I tried to create an IF formula relating
the data in the two sheet to fill out the row with corresponding data,
it didn't work..

Thank you soo much for you help!!!