We were in an unranked draft. I was adc and picked pantheon and another guy was supp and picked bard. Another guy on our team got mad and said "WTF is our bot lane doing?!" and then proceeded to leave. I'm still new to the game. So, which champion is suppose to go bot as adc and supp?
ranged autoattackers - check the marksman class
A good champion for both supporting and adc could be ashe with her slows/cc ult. She's also ok ish at kiting and peeling and can kind of clear turrets quick. only real down side to her is she has no escapes and is a pretty bland champion.
Good champions for adc are tagged as marksman 
and others. They usually have long-range autoattacks and some 'steroid' that usually means AD bonus or AS bonus to enhance their basic attacks further.
Good champions for support will be tagged as 'support' or as 'tank' 
and others. The only real requirement though is to be of value for their team while lacking gold, so sometimes you will see a fighter or a mage used there.
Pantheon is not adc, even though his damage is high. You can make it work in lower levels, this is called a 'kill lane' i.e. 
+ , but your teammates will sometimes freak out because they think you only should play meta champions.
ranged ad champions are supósed to be Bot.
Bard was totally fine
