procedure TForm1.Button1Click(Sender: TObject);
var
Doc:IHTMLDocument2;
input:OleVariant;
userinputelement,pwdinputelement:ihtmlinputelement;
begin
doc:=webbrowser1.document as ihtmldocument2;
userinputelement:=(doc.all.item('username',0) as ihtmlinputelement);
userinputelement.value:=edit1.text;
pwdinputelement:=(doc.all.item('password',0) as ihtmlinputelement);
pwdinputelement.value:=edit2.text;
end;