in which i want to erase what's in it, to then back up all my data that's on my Macbook pro using time machine. I did this once before, but I totally forgot how to. Please help. It's urgent. Thank you =)
Use the Disk Utility in the /Applications/Utilities/ folder to reformat it as Mac OS Extended (Journaled), open the Time Machine pane of System Preferences, and select it.
Retrieving data ...