Here is a short video that shows the fundamentals. I don't have sound on this computer, but the visual of using the tape measure on front and rear of tires looked good, and may get you started.
It is hard (usually impossible) to get the tape up as high as the axle both front and rear; just do the best you can. Also, spin the tires to see if a tread rib is running true enough to measure to. If not, then you may need to paint/scribe/ink suitable point while rotating the wheel. Lastly, the suspension must be all settled in its normal condition when checking toe. This means you must roll the car a turn or two of the wheels if it has been jacked-up recently. Oh, yeah, get the wheels in the "straight forward" position as well as possible.
Difference between front and rear is usually in the 1/16" to 1/8" range, and the rear dimension is usually supposed to be the greater one.
I would ignore those videos showing use of a string stretched from the rear wheel across the front wheel. That will only work if the rear wheel width (outside of left to outside of right) is the same as the front, which often isn't the case, and if the front and rear wheels track exactly the same.
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