You need to contact the sellers listed in the link ... show some self-initiative, because 99% of the questions you might want to ask, have already been asked by other people and the answers can be found in this forum.
You only have to search for it.
I don´t want to discourage you, but it takes time plunge into this issue.
So read, read, read.
I sense that you want to rush into your armor, but like many of us, who started with this stuff, you have to learn to be patient.
You have to make up your mind about what kind of armor you really want. What episode (see http://starwarshelmets.com/)?what material?where to buy?do it yourself? buy an already built one?
Take your time, read carefully and when you have any questions after this, just ask them.