Re: dishwasher drain line
The air gap is typically an ugly little chrome dome that pokes through top of the counter or sink. (If you have an unused hole on your sink -- this is the place for it.) The drain line from the dishwasher hooks to the air gap underneath the counter. From the air gap, another hose connects to a "dishwasher tee" that is on the sink's drain line between the strainer basket and the trap.
The folks at any small hardware store or plumbing supply shop should be able to illustrate this to you, since they'll have all the parts right there. The big box will have the parts too, but if they ask "what's an air gap?" or they send you somewhere other than the plumbing department, that's your cue to get away quick before the stupidity rubs off on you.
The "Senior Member" designation under my name doesn't mean I know a lot, it just means I talk a lot.I've been a DIYer since I was 12 (thanks, Dad!). I have read several books on various home improvement topics. I do not have any current code books I can refer to. I was an apprentice plumber for two years.