I'm still confused by this place!

[sanctuarysarah]

I was wanting to make changes to my header and theme, perhaps add ones to do with Sanctuary that I've discovered in the communities.However.....I have no idea whatsoever on HOW to change them.Which part do I click on to get to the bit to change it all.I'm so fed up with the one I have and want prettyful Amanda Tapping/Sanctuary ones!!!!!!!!!

Someone please help me. :(