Microgreens are flavorful and nutrient packed tiny young edible greens from a vegetable, herb, or plant. The plant is harvested by cutting it at soil level when there is only a single shoot with 2 tiny leaves. Their flavor is amazing, I love them in salads. My favorite microgreens are sunflower, arugula, and radish.
I recently tried my hand at growing sunflower microgreens in a Southern exposure window in my house and am thrilled to report it was easy and within one week, I was harvesting.
You're going to need a warm, humid enviroment to get your seeds to germinate and something as simple as a bowl covered with saran-type wrap will work, but I purchased a set up at my local Gardening Center to make a tiny table top greenhouse becasue I will use this again and again to start other seeds and/or grow microgreens.
If you want to replicate what I did, here's what I bought:
1) Two generic plastic seed starter trays, $0.99 each. One tray has holes in it, and the other tray does not.
2) A domed cover that has vent holes and fits on top of the trays, $0.99
3) Organic seed starting soil, $4
4) Sunflower "sprouting seeds", but I did not follow the planting directions on the packet. I wanted organic, non-GMO seeds ($3.99), but any sunflower seed will do. 
Directions:
1) Soak the sunflower seeds in room temperature water for several hours and then drain them right before you're going to plant them.
2) Fill the tray with holes 3/4 full of soil. Water that soil to completely saturate it. 3) Lay a densely packed layer of sunflower seeds on top of the soil.
4) Spoon more soil on top of the seeds to lightly cover the seeds.
5) Mist the soil with water, you dont want to disrupt the seeds.
6) Place that tray on top of the other tray, the one without holes, and cover with saran or the lid you purchased. Keep the venting holes closed.
I like this brand of seeds, disregard the "sprouting" instructions on the back: 
Within 24 hours the inside of your little greenhouse will be all fogged up and have beads of water clinging to the walls. Do not open or disrupt the vents. Mother Nature is working her magic. Within 48 hours you will see tiny shoots pushing up through the soil. At day 5 you can uncover your greenhouse. At day 7 you can harvest your microgreens. Use a scissor and clip the greens right at soil level. Refrigerate what you do not eat immediately. You can now start the whole process over and plant again. While your next crop of greens are germinating and growing, you'll have fresh microgreens to eat.
Enjoy!!