Hello. I am remodeling my kitchen, including replacing the sink. I currently have a single bowl and was considering switching to a double bowl. I am also going to install a dishwasher (I do not have a garbage disposal and was told I do not need one). I was just wondering what each job entail, updating for a double bowl and installing the dishwasher, and whether it is something I could do myself or something I would need a professional for? Thanks.

The important thing to remember is if you have one drain, you have one trap(goose neck) under the sink so you don't have venting problems.

What you need is a "Y" tailpiece, a regular tailpiece, a continuous waste, 2 sink strainers and a single trap. The "Y" tailpiece connects on the sink strainer closest to the dishwasher. The dishwasher drain hose goes to the highest point inside the kitchen cabinet (to prevent water from backing up into the dishwasher from the sink) and gets connected to the side outlet of the "Y" tailpiece. (Some codes require an air gap fitting). Put the regular tailpiece on the other sink stainer and connect the 2 tailpieces together into a single drain with the continuous waste. The trap gets connected to the tailpiece outlet of the continuous waste and into the drain. When you install the sink strainers use plumber's putty for a water seal.

Happy Plumbing

I have a different take on the installation. This doesn't involve a wye. After you trim out and install the sink you will come off the stubout into a trap. Depending on where the stubout's located, center or one side, you will connect the two tubs to either a center outlet or end outlet continuous waste,(see mages);.
The dishwasher will connect to a branch tailpiece,(seer image) after first running a high loop, (see image) on the washer hose. More questions? I'm as close as a click. Tom