macro prompts immediately to open a file once the Excel file with the macro is opened

Hi
I am looking for a macro that will immediately prompt to open a new file when the Excel file with this macro embedded in it is opened (without having to initialize the macro). thanks!!

Do you mean open a new file (create a brand new blank workbook) or open another file, the name and location of which are known, or open another file in an as yet unknown location (ie requiring user input)?

open a new file requiring user input. I want it to open data from another file (possibly on a flash drive or other). I will then use other macros to further edit the data. thanks