Filling Contact Information Automatically for MailMerge

[jjenkins90]

If I am formatting a spreadsheet to use for MailMerge address labels and I want my spreadsheet to reference another page and automatically fill the addresses of particular high schools, how would I do that?

For example, I have a list of 500 high school seniors with their high school name that I would like to contact and I have another spreadsheet with every high school in the state with its mailing address, how do I make the addresses automatically fill with the corresponding high school?