Ok, I'm sure this is a lame question that's been asked a zillion times before but, I'm totally new at this stuff and want to get information from people who're good at this and can explain it in normal terms. I've gotten the hang of using characters with built in textures but, if I reskin a texture and want to apply it to a character, how do I go about it?

The answer will depend on which version of poser you are using. Poser 5 will allow you to meld multiple textures to group/figure in Materials room. In p4 - is under render materials and you can apply a single texture to part or full figure. Would suggest a jump to here: http://www.fallencity.net/lore/p-transparencies.php Very good tutorials. Plus the very generous and informational Dr. Geep stuff there.