An Uncapitalised Intro into DnD 3.5 Classes
Barbarian - big fuck with axe. or hammer. or axe AND hammer. you will hit stuff, you will yell, I will probably give you bonuses if you yell irl. usually dirty and angry, but you could also be clean and angry if you really want.
Bard - skinny fuck with lute. or flute. probably not lute AND flute because you are a useless piece of shit. you literally just run around singing to inspire your comrades, and then write a poem about how you took Baron Dickcruncher III on all on your own. if you sing irl i will kill your character.
Cleric - you love god, and god loves you back. you will heal friends, you will turn the undead to ash, and you will probably do some specific weird shit based on the specific weird god you create. feel free to creep everyone else out by being a bit too intense about tentacles.
Druid - you love nature, and nature loves you back. you will heal, uh, plants I guess, but mostly you will use the forces of nature to crush, burn, freeze and otherwise maim your foes. you get a pet and at some point can turn into an animal. feel free to creep everyone else out by being a bit too into horses.
Fighter - this is the super boring class, but it can do some cool stuff if you really get into the mechanics of the game. Aragon was a fighter so you can be him if that gets you wet. you want any specific combination of weapons and leadership and this is pretty much your jive.
Monk - this is the super racist class. you are a mystic warrior from whatever qualifies as the Far East of the setting, even if the setting IS the Far East. you know kung fu and can do some really vague kung fu shit, but mostly you will punch limbs off people all day.
Paladin - you are the bestest ever person in the world and you are always right about everything, ever, because your god is always right about everything ever. if you want to not have a god and just worship your own reflection I will allow it because it's pretty appropriate. you will have plate mail, a big weapon, and the ability to fry evil things with white fire. also probably heal people, but you'll be a dick about it.
Ranger - the Legolas class, but also with a sweet pet. you are at one with the forest, but you can also hate specific kinds of creatures so much you are extra good at killing them. I only just realised how fucking weird that is. bow or double swords is the standard, and you get some cool combat tricks and, eventually, some nifty nature spells like a druid
Rogue - the sneaky lil shit class. you can make and break traps, pick locks, hide behind basically anything and if you stab someone while they aren't looking it does absolutely sweet damage. you are also probably way more concerned about your own safety, and your treasure hoard, than anything else.
Sorcerers - you are a font of magical energy the likes of which this world has never seen, or at least you like to think so. your powers come from somewhere spooky, you're not really sure where, but you shit fireballs sometimes and that's cool. you don't have many spells, but you can use any of them at any time (this is unique). think lightning, glowy runes, magical growth, exploding everythings, and running out of spells right when you really need them.
Wizards - you are a font of magical energy the likes of which this world has never seen, or at least you like to think so. you have practised for a long time to be able to use magic, and it kinda shows. your powers are a lot like a sorcerer's, but you have a few more at any one time. motivations are probably focused on taking over the world, but mages are kinda weird people and I don't wanna presume.
Lastly. Remember that DnD is about making shit up, so you can play these classes any way you want, or try to figure out something else cool that you wanna be. Let the DM sort it out, and if they can't, get a better DM.