how do I change the radiator?

i have a 2005 dodge neon other day I noticed steam coming from under the hood i popped the hood and the over flow was dripping i didn't think it was a big deal so i let it sit a few days later i open the radiator and it was very milky looking i smelled it I have more questions as i proceed ill tip for sure? I have a 2005 dodge neon other day I noticed steam coming from under the hood I popped the hood and the over flow was dripping I didn think it was a big deal so I let it sit a few days later I open the radiator and it was verey milky looking I smelled it and it was transmission fluid after search net figured out to replace my radiator. Anyway to the question how do I remove the transmission lines from bottom of radiator the look like they are just stuck into the nut of the radiator I dont wanna break the lines and cause more problems.2nd question if I unhook tranny lines is it safe to flush old radiator or do I wait to put new one in and flush I dont want to get gunk in new one if possible