Making parboiled greens requires cooking in boiling water first before continuing the process with another cooking method, such as sauteeing.
You can use the stalks or not. But if you DO, then you can just leave them attached to the Greens.
Boil a pot of water. Add the greens and cook for just a few minutes, until the colors are vibrant. Carefully remove from the water and drain completely. Your greens are now parboiled and can be used in any way you'd like.
This technique is a wonderful way to keep the colors bright if presentation is important. Another reason to use this technique is if you're preparing a stir-fry -- you can parboil all the veggies first so they finish stir frying at the same time. Or you can saute the greens in a bit of extra-virgin olive oil until tender.