There are four (4) steps to the INDEX/MATCH function, each separated by a comma.
1. INDEX: Identifies which specific column from the table (or range) that contains the data you want to bring over.
MATCH
2. Lookup_Value: The common identifier from the final dataset that can be used to connect both data-sets.
3. Lookup_Array: The column that contains the common identifier from the “helper” dataset that can be used to connect both data-sets.
4. Match_Type: Exact Match = 0, you’ll always want to enter 0.
Remember to use $ symbols to lock in the range! Please refer to the image (you can click on it for a larger view).