Try this:
in webform1 write this on a button click:
protected void Button3_Click(object sender, EventArgs e)
{
Response.Redirect("webform2.aspx");
}
or this:
protected void Button3_Click(object sender, EventArgs e)
{
Server.Transfer("webform2.aspx");
}
both will work.
hope it helps :)
for further queries comment here!