Code to Find and Replace Userform Values

I have a macro that takes ~50 excel spreadsheets, and takes data out of them and compiles it into a "Raw Data" sheet.

What my userform is aimed to do is allow the user to change all the headers in the Raw Data to what they want.

The sample userform is attached.

What I want the macro to do, is take the lab series number (left hand column), find all of these instances in the excel worksheet and replace it with the correlating vendor name (right hand column).

Thanks for the help! If you need any more information let me know.