Checking to see how you'd use the code somewhere else is more complicated than opening the workbook yourself (you can cut and paste this code directly into your macro)
Dim Flnm as string, wb as workbook
Flnm = "[Workbook file path and name]"
set wb = workbooks(Flnm)
and then preface any references to that other workbook with wb. (as in Workbooks.activesheet etc)
Remember that thisWorkbook is the assumed default for any sheet references like ActiveSheet so if you want to refer to another workbook you just specifically identify that you want to get the data from that other wb.
(It isn't clear which value in your code you want to get from that other sheet or I'd be more specific)