I need to know how I would go about taking a toilet drain and turning it into a drain for a washing machine.

I need to know how I would go about taking a toliet drain and turning it into a drain for a washing machine.

Simple answer? You're not ! Not without extensive rework you're not.
A toilets closet bend and drain line is a unvented horizontal line under the cement. You can't just discharge the washer into the open hole. That would be opening up your home to a open sewer. For a Washer trap and standpipe you need a vertical dry vent in a wall to install a sanitary tee and trap with stand pipe to. That's simply not available in a toilets drain line. I've drawn a little of the drainage set up for a washer so you can see how it's done. I'm afraid your plan just isn't going to fly. Sorry, Tom