Http post

I am using pub.client:http service to post username and password to some url. I am providing 2 inputs to this service: username and password. In serviceIn, I am hard coding the value of url, https://someurl/LoginPage and the method is post. This
LoginPage has an action which redirects to the successful login page.

I want to know how can I get the login successful page after I post http request.

Do I have to write some dsp pages for this?