the Jessica up do has a separate piece i think, it's quite difficult to create such heavy volume with the hair that's left when you
when my hair's looking all weird, i do really simple up-ish do that i find really easy to do, and people believe it's complicated and impossible to do.
it starts with a simple ponytail, it has to be a little tight because that's what's going to mantain the hair in its place. the placing is also important: if you want an middle-up do (like Jessica's ^ -above) you're going to do the ponytail in the middle, if you want an up-up do, you'll do it higher.
when that's done, you divide the hair from the ponytail into sections. first you take one section and start twisting it, and you roll it on your finger as if you were curling it. then you put a clip (those metal straight thingies that use in salons) to keep it in place. you repeat this with the other sections, and that's that.
i think i explained it in a messy way and it's hard to understand, so if you didn't get it i could try and take pictures or something