Event Editing, Help A Noob Plz~

So, I'm sitting down to start my first piece of event editing. I've got the recommended things, like Level Editor, Windhex and all that. Currently, I'm just starting out with the intro, you know the bit where we assign the properties of Terra, Wedge, and Biggs. Now, I'm at the spot in the rom on Windhex where this event takes place, and I see the values that match up with the dump of the event values. However, what's boggling my mind is I don't see how to really... change them? For example, I'm wanting to replace Biggs with the character in my Leo slot and want to Wedge to have my Banon's sprite, along with changing their preferred palette's. So, how exactly do I go about making these changes?