Stick it in the ground and stand back. It grows rather well I love it last year was the first time for me and is was prolific with no fertilization though I would think a light hit of good nitrogen would help it row even better. I planted some seed and am waiting for it to pop.
But basically Swiss chard is of the beet family it is just harvested for the green and not the bulb. Hopefully you got the bright lights variety as it is very colorful as well. I grow it as lettuce some people use it in place of spinach. I always just chopped it up with outer lettuces and it was great.
It should do fine through the summer and all the way to first frost, it may even comeback in the spring if cut off at ground level.
I also remember hearing that is is barely bothered by disease of pest so bonus there, everyone should have some chard growing in there garden in mu opinion.
One more thing you harvest as a cut and come again just don't take more that 1/3 of the plant, that is the basic rule for plants of this nature.