First, we cook the rice. It's important to rinse the rice thoroughly (until the water runs clear-ish), scrub it gently, then rinse again. This removes extra rice bran and improves the flavour and stickiness. Yes, you are taking away some of the nutrients--if you really cared about those you'd be eating brown rice anyway.
I'm assuming you use a rice cooker. If not, just look up the directions for cooking rice in a pot. It's not that hard. My tip for cooking rice in a pot is to put a dry towel under the cover after it cooks to catch any condensation that can ruin the rice by making it too mushy. Anyway, fill the pot with to the line indicated, and throw in your dashi granules and combu strip and give everything a stir. Cook according to directions.
For the eggs, just throw all the ingredients together and beat it, but not too hard. You should still see a bit of the white congealed together, like this:

From
Top Chef Fakku June [take2]
I actually beat it a bit more after the pic was taken, but you get the point--don't beat the eggs too much, you egg abuser, you.
Heat your pan to medium or medium low oil it. Now, here comes the difficult part. We want to make the egg in thin layers of only a couple tablespoons per layer. Put a bit of the egg and spread it thinly, cooking until the top is still slightly wet.

From
Top Chef Fakku June [take2]
Now roll the egg using a spatula and fork, or really, any two cooking implements you want. Or if you're really good, you can just use a pair of chopsticks. I use a spatula and chopsticks, scooping the bottom out with the spatula and rolling with the chopsticks. Try to get the roll as tight as possible. Re-oil the pan if necessary, then add another thin layer of egg.

From
Top Chef Fakku June [take2]
Roll, rinse and repeat until all the egg is finished. Pro-tip: it's better to roll too early than too late. If the a part of egg is a bit wet when everything is done, you can always pop the whole thing into the microwave for a couple of seconds to set it. But if you overdo the eggs, the layers won't stick together properly and will fall apart when you try to cut it. Anyway, roll the eggs on a sushi mat or wet towel covered in saran wrap until it's tight and vaguely rectangular-shaped, then slice it. I usually just eat the ends right then and there because they will be uneven unless you use a special rectangular tamagoyaki pan (but who has those, anyway?).
Remember that I told you not to beat your eggs too much? This is why:

From
Top Chef Fakku June [take2]
You don't get that beautiful marbling from overbeaten eggs.
Anyway, back to the sushi rice. Just throw all the ingredients of the sushi-zu together in a microwaveable container, stir well, and nuke it for about 30 sec or until the salt and sugar dissolve. Fish out the combu strip and gently fold the mixture into your cooked rice. You don't wanna mash the rice, just stir and fold very gently. Wait for the rice to cool a bit (you can fan it to speed up the process), then mold the rice into a bite-sized rectangular shape and put the tamagoyaki on top. You can also wrap a bit of nori around the whole thing to keep it together. You can just eat it as is, or if you're weird like me and put wasabi on freaking everything, you can eat it with wasabi and a bit of pickled ginger. I made the pickled ginger too, but that's a recipe for another day.