Hunkie, Amaranth is super easy to grow.
It's in the Chenopodiaceae family along with beets and spinach...so is quinoa and pigweed, oh, and I think celosia is considered in the same family. Botanists might be splitting the family up because of genetic discoveries. The pigment in Amaranth sure smells and tastes like Beet pigment. All parts of the Amaranth plant are edible.
Most of the Amaranths available in seed catalogs grow with their plant architecture vaguely resembling sunflowers.
A tall single stem that grows upward.
Most of the garden Amaranths fit in one of 2 categories: White seeded...actually golden. And Black seeded, actually an intensely dark magenta.
Bountiful gardens' Ellen Bartholomew has developed a white seeded red flowered amaranth.
The white seeded Amaranth grain is the most preferred for flavor. The black seeded grain is used more as an additive like poppy seeds.
One very important thing for the first time Amaranth grower: (anyone who has grown it will understand why the capslock was used

)
BE VERY CAREFUL ABOUT LETTING SEEDS FALL TO THE GROUND, ESPECIALLY STARTING WITH THE FIRST TIME YOU GROW IT!!!!!
(hey guys, did i add enough of these !!! things?)
Amaranth reseeds<<<understatement of the year.
Now that my main seedling weeds are Amaranth I get plenty of finger and thumb exercise, and I didn't even have to pay to Gold's Gym anything for membership! How great is that???
On the other hand, Amaranths are beautiful and satisfying to grow, and look real good in with some of the shorter sunflowers.
If planted too closely, Amaranths will make small plants. A foot between plants will get you full sized plants.
Some kind of corralling or staking helps keep them upright, just like sunflowers.
For looks the red flowered varieties are the winners in a close race.'
For flavor the golden flowered are the winners.
Let me know if you grow them, and I'll let you know how to harvest and thresh them.
Oh, Quinoa is similar, but the leaves are more like pigweed leaves, and to produce grain, many kinds are more finicky to grow. Colorado Quinoa is easiest, and it grew very well and produced well for me too!