for f:=0 to WebBrowser1.OleObject.Document.forms.Length-1 do begin
form:=WebBrowser1.OleObject.Document.forms.Item(f)   .elements;
for i:=0 to form.Length-1 do
if form.item(i).name='login' then 
form.item(i).value:='test1'
else
if form.item(i).name='firstname' then 
form.item(i).value:='test2';