How to add 2 applications in one solution in c#?

Question

Hiiii...

     I have two applications related to each other and i want to add these two applications in one solution. I have one form in which two buttons, when i click on one button the particular application should be run v/s same for button two. so how can i do this. Please give me solution for that.

Thanks & Regards,
   Atul Pote