water, enough to cover (see directions)
Use a rice cooker. It just makes it all easier.
First you have to use sushi rice. Because of the starch content, the rice must be rinsed. I usually rinse it about 4-5 times or until the water is about 20% clear. If you rinse off too much starch, the rice will not be sticky. Drain the rice and let rest for about 20 minutes. I use my hand for measuring the water I put back into the rice. I lay my hand flat palm down, on the rice and add enough water to reach the middle knuckle of my middle finger. This works with any amount of rice that I cook, one pound or 10 lbs. If you are going to use a measuring cup, then 3/4 cup of water per cup of rice.
Put the rice in the pot and cook for 25 minutes.
Remove the hot rice into a mixing container, a wooden bowl is traditional but plastic works great too .Mix the sushi vinegar ahead of time so that it is cool before it's poured over the rice. I use a wooden spatula for mixing my rice and sushi vinegar. I pour sushi vinegar over my spatula to spread it over my rice more evenly. Cut the rice with the edge of the spatula, don't stir or beat the rice. It should be folded and fluffed gently until all the vinegar is absorbed. Cool until about room temp or a little warmer. Warm rice rolls easier than cold rice. Cover the rice with a clean damp towel in between uses. This keeps the rice more pliable and easier to spread. Sushi rice can be kept overnight at room temperature if covered with plastic wrap.
One last tip, if this all seems like too much work and effort, then call the nearest sushi restaurant and just order the rice you need from them.