Activation

I'm trying to activate my Office software. It says I need a 25-number
license key and press "convert..." OK. When I press it, it takes me to a
menu that says: "Add/Remove features", "Reinstall or Repair", and
"Uninstall". Where would I put in the key? And also, if I reinstall, does
that mean I lose the email in Outlook?

=?Utf-8?B?YXJvbm55Yw==?=