When finding an area for the spinach, they will need full sun to grow!
In the video, we mention making little rows to put your seeds. Think of it like the rows you see in large scale agriculture. They make the little groves 1/2 inch deep, sprinkle the seeds and you'll have a little area for them. You can also just make little holes 1/2 deep spaced 2 inches away from each other!
It'll take about 45 days for you to see all of your spinach grow fully, but feel free to take some as they grow. Just make sure not to harvest more than 1/3 of what's grown at a time!