Vlookup in Access

Hi

I have two tables with data in Access called "118" and "Mapping":

In "118" table I'll have my monthly data, which will show amounts (in my case 1 row equals one item/amount), by ZIP code. In "Mapping" table I have two columns which is all ZIP codes and their allocated Clusters.

What I want is to have a field in "118" showing Clusters. Hence, when I dump in data each month/quarter the field just autopopulated. Basically like a Vlookup function in XLS.

I'm a beginner in Access so can't do programming and all this.

Hope you understand and can help.