How much do I tell new players about new monsters?



Background

I am a brand-new DM, about to lead a game for brand-new players. I have a lot of knowledge of rules from playing Baldur’s Gate and Neverwinter Nights over and over, leafing through a friend’s books, and finally buying the three basic books for myself.

Question

How much information should I give to my players about monsters they encounter?

Should I essentially read the entire MM entry to them, or let them figure out how the enemies operate through experience, or (as I assume), something in the middle? Keep in mind, only one of them has even peripheral experience with D&D (they are very good sports for giving it a shot!), so they won’t be bringing background knowledge to the table. For example, do DMs generally let players know what immunities creatures have, or do they let them figure it out by trial and error? What about offensive abilities? For example, if a player has a potion of fire resistance, should I give them a heads-up about the fact that the chimera they’re facing has a fire breath attack?