Whenever I play my mage, i cant cast the damn spells fast enuff to kill 'em quick,
so my question is how do u cast the spells quicker? enemy mages burn me by casting
tons of magic missiles my way before i get off one...(i'm a newbie, to explain for
the simplicity of this question

The best way to stop a mage from casting a spell is to disrupt him/her while or before he/she is casting a spell with missle weapons, magic and normal.

The other thing is you need to make use of you your quick spell button on the bottom bar, preselect a spell that has a short casting time to use first then somthing a bit more heavy duty for your second spell.
When casting spells use your space bar to pause the game and select your mage (let the NPC's do their own thing)cast the spell then pause as soon as your mage has cast a spell then select the next spell repeat this process until all your enimies are dead. Dont be to concearned about your NPC's getting caught in back blast of your spells they will get over it.

Another way to stop a mage is to use your cleric NPC to cast silence 15' radius on them but make sure your mage is outside the area of effect, this should keep those nasty mage's quite unless of couse they have the spell vocalise this will negate the silence spell.

Another trick is to cast invisibility on one of your NPC's (or your thief in stealth mode) and use him/her as a forward observer to sus out where your enimies are and then move to just outside your enimies range of vision and start casting area affect spell's like fireball or stinking cloud, Beware that undead are suposed to be able to see invisible creature's. Ps, its a good idea to turn off the AI when doing this so your NPC's don't go doing their own thing.

I also suggest that you read the desciptions of spells and potions to use them to their best affect somtimes the most unseemly spell can be the most affective. Good luck.