How can I use soft pastels with an easel? I am a beginner artist, and have been exploring the medium of soft pastel for some time now and I absolutely love it. 

Recently I was looking into different kinds of easels and which one to buy. But I noticed that the tripod easels (even the ones that are specifically made for pastels) don't come with any boards, they just come with an horizontal metal or wooden piece to place the canvas on it, and a top piece to hold the canvas in place. But this does not really work for me since I paint on soft pastel paper and need to apply some pressure on it, so I will need some support for the back of the paper like a board or something.

This is the easel I want to buy on amazon, it is cheap and sturdy.

So my question is how do pastelists use such tripod easels for their art, and what can I do to make this easel fulfill my requirements?
You use a drawing board. When I was in high school we used these for our drawings and paintings all the time whether using an easel or sitting at a table. It allows you to easily move the paper around without touching it as much and gives you something to hold onto. I remember we taped the paper down to the board to keep it in place.

Here's an example of a similar easel on Amazon and it includes an image of a drawing board to illustrate how it's used (it doesn't include the board).