Changing Task Owner From "Unknown" to my name

Hello,

I searched for "task owner" before writing this question and did not find
the answers to my specific questions.

My questions: How do I change the owner of a task from "Unknown" to my name?
Why do some show up as unknown and some show up with my name on them? I
don't recall the opportunity to state the owner.

I am using Outlook 2007, Windows XP, and Mozilla Firefox. There is no one
else using my computer, which is at home. I want to be able to show only
tasks in the to-do bar, and not every single blessed email that I might have
flagged for whatever reason.

Can someone please answer my questions?

Thank you very much.

Candy