How do I create a random number generator in vb.net

Hi i want to make a random number generator that just creates random expressions

This is for a math game project i have. My problem is that right now i dont understand the random generator.

Like i just want it to create a random 2 digit integer then an operation then another random 2 digit integer. One random expression generator will generate subtraction and addition problems, while another will generate multiplication and division problem

like this

23 - 78 48-55 24 + 16