There are several crackle products available and art and craft stores. The one I use is by Plaid.

The first step is to paint your page.  You will need two colors for the crackle to show up.  The bottom coat is what will show up through the cracks of the top color.  I painted the first coat black.  I am not precise or patient with anything I do, so I used a heat gun to hurry up the drying process.

When the first coat is completely dry, apply a coat of the crackle medium with a brush.  Put it on fairly thickly.  If you want neat, uniform cracks, apply it evenly. I don’t because I like it to look more natural.  Again, I use a heat gun to hurry up the process.   Dry it until it is tacky, but not completely dry.

When it just feels sticky to the touch, but isn’t wet, apply your second coat of paint.  You can dry this coat with a heat gun, too.

As you dry, you will see the cracks begin to form.

Close up of the cracks

You can use this as a background for gluing paper items, painting or writing.  Keep in mind that the surface is not smooth when you write, though.  You’ll need a pretty substantial marker.