Write from page1.aspx (site1) when HyperLinkField is cliked, to input type="text" from page2.asp (site2)

I have an webpage (C#- http://localhost/site1/page1.aspx) and when I click a HyperLinkField I open an webpage (http://networkip/site2/page2.asp).  

I can modify page1.aspx and I can only view the structure of page2.asp.

The page2.asp file has 2 input type="text" and the form method is POST.

I want the write a information in this two input when page is opened.

Is it possible?? And, if the answer is yes, how can I accomplish this.

An interpretation would look like this:

page1.aspx.cs
protected void hlNavigate_Click(object sender, EventArgs e)
{
  Open ("http://networkip/site2/page2.asp");
 (http://networkip/site2/page2.asp).textboxT1 = "First Information";
 (http://networkip/site2/page2.asp).textboxT2 = "Second Information";
}

I appreciate any help.