how to use the 1st page control name to another page

i designed a page using controls like textbox and labels in my first page,actually i have a grid view in second page,that page name is viewgrid.in that gridview i provide a view option,if i click the view option of the particular selected gridview rows  it will displays,i want to display in my first page using its control names,while providing the code txtfname is not declared is shown like this error.how to use the first page control names to second page and display it in first page...

 txtfname.Text = row.Cells(0).Text
            txtlname.Text = row.Cells(1).Text
            txtecode.Text = row.Cells(2).Text
            txtcompany.Text = row.Cells(3).Text