postURL :='ip..../login.php';
res := TstringStream.Create('');
Memo1.Text :=Format('username=%s&password=%s&submit=login',[edit1.text,edit2.text]);
self.info.Caption :='Wait Verify...';
try
self.IdHTTP1.Post(postURL,memo1.lines,res);
except
end;
s1 := res.DataString;
s1得到的就是登陆成功后/或者失败以后的内容
具体的去看idhttp的帮助。很简单的