I am completely new to this game, but I find it fascinating. I feel really stupid, but I can't seem to figure out how things work.
How do I memorize spells? How do I read all the books and remember what they say? How do I get my cleric/mage to cast spells?
I'm only in the circus tent, but I'm stuck! Help...please?

Read your manual...Or play through the Introduction to get to know how to use the interface.

<font color=cadetblue>Firstly, welcome to IW! [img]graemlins/happywave.gif[/img] Memorizing spells is easy. On the left side of your screen are a bunch of menus. 1 of themis the wizard book (hotkey w) and the priest scroll (hotkey p). When you click them, you can pick spells you want to memorize. After you pick them, hit your rest button and when you wake up, your spells are memorized and ready to go. When you want to cast a spell, press the cast spell button at the bottom of the screen (looks like a crescent with 3 stars).</font>

Welcome to IW! [img]graemlins/thewave.gif[/img] I suggest that you play the Tutorial... it will all be reveald.

adn try this site
http://www.geocities.com/sixospades/bg/bgguide.htm
which will answer most of your questions regarding gameplay. Think of it as asecond manual. If you need any tactics either search the forum for old threads on Dragonslaying, Undead, Illithids (you'll know what they are when you meet them :D ) or just ask.
P.S.:Try to delete that double-post :D