Given two (or more) workbooks where A needs data from some other workbookB.cell,
in Workbook A at the location desired enter
Notice the sheetname!cellreference is how to get data from one sheet to another in the same workbook
so adding the [pathname] just addes the workbook location.
If you need to navigate on the directories, just start to enter =workbook and tab to get the file browser.
This will then create an absolute path the the file, eg