Where are you having problems ?
Can you attach the workbook with the data joined and where you're stuck ?
Yes, I can see XLS, CSV and TXT files .... no TWB or TWBX file though
Everyone here is happy to help you when you get stuck, I don't think many are happy to complete your assignment for you though.
If you join all the data in Tableau, create the graph that you're after (so we can see where you are stuck) then save as a packaged workbook, it will be a lot easier/faster to help you