DIY radiator flush in 2000 dodge avenger?

I need to flush my radiator there is some nasty gunk (kind of greenish) in my overflow container and on hose that goes in it.. probably cause when 2 ear ago i mistakenly poured windshield washer fluid in the overflow insteadof anti-freeze.. i know, i know.. stupid..anyway its all crappy and the overlow is boiling and steaming.. i think it needs a flush..sounds like a clog cause when i pour antifreeze in the cap the next day theres none left and when i look at the overflow cont its boiling after i drive..is there a drain hose..how do i do it?does tis sound like thats what i need??thnks/