Write(float h, string txt [, mixed link])
h
txt
link
// Begin with regular font
$pdf->SetFont('Arial','',14);
$pdf->Write(5,'Visit ');
// Then put a blue underlined link
$pdf->SetTextColor(0,0,255);
$pdf->SetFont('','U');
$pdf->Write(5,'www.fpdf.org','http://www.fpdf.org');