Excel help

hii

My excel sheet contains the list of my sales to customers every month.
I want a sumary sheet i want that it shouls show me what all has been sold to each customer in front of respective customer name.

i have used sumif formula but in creteria i want it shoould take the name of the customer from the cell where customer name is there so that when new customer is added it should automatically reflect in that.

Pllls provide me with the sutaible formaula.

Thnnks
Manish