For the inner lining, you can outline the envelope on an 8.5x11 piece of printer paper and cut 1/2 trim around it until your sample piece can easily slip into the envelope. Once you have the right size you can use your sample cut-out as a template to cut the specialty paper. I then used 2-sided tape to secure the edges on the triangle part of the envelope, you can use a small amount of glue, but be careful as this might create ripples.
The actual card was made up of black construction paper, glitter paper, and card stock. I used a few sheets of printer paper to create a sample set so I could determine the sizes for the black, glitter and card stock papers. I then used the sample sheets as my templates when cutting my good paper. I cut out the quantities I needed out of each of my substrates and then glued them together. Since I was working with glitter I went with a glue gun.
I found free swirls online and layered a few of them together (in photoshop) to make the header style on the card stock.
This piece has the construction paper, glitter and card stock as well. It looks like there's a fourth layer in black, but it was actually printed on the card stock as a black border to create the illusion of an extra layer. I also needed this color separation because ivory against the silver backing was not very flattering.