I really don't know any better way to name it.
I have a link to forums in my website where clients have to login to the forums after they clicked the link.

What I would like to do is have the ability to login from textboxes that are put on my website.
They would enter their user name and password on my website and then click submit.

What I need done is to have the information that is inputed on my website be entered into the proper fields on the forum website.
I don't know if this is possible or even legal.

But if there is a way to have information input'd in one website appear in the proper fields on another website and then executing the action of logging in.
If you have any feedback it would be much appreciated. Thank you for your knowledge.