How to open multiple sites by using vb.net

When we click on a button multiple sites are open in Mozilla or internet explore in tab .......

i have tried this

System.Diagnostics.Process.start(webiste name)

but it open only one site at a time.......if we write this line two time on click event it open second website like this
System.Diagnostics.Process.start(website1)
System.Diagnostics.Process.start(website2)

but i want to open both website........

Plzz suggest..........