Facebook Passsword

Hi

I have a box popping up on my desktop that says

Facebook Password

Enter the password for "my email address" in System preferences. I have looked for a place to enter in the PW but can't seem to find it?? It shows the email in my preferences but every where I click there is not a spot comes up to enter in the PW. Thanks I know I am probably overlooking something very simple 🙂