Login Information to another site

I am very new to any type of coding so bear with me…

Currently working on a site where they want to have a login page, and they want to use that information the user sends in to redirect to another site, and log into that. (think of if you had a login page on a portfolio site, and you wanted to log in to facebook from that portfolio site )

I have a list of commands that are usually written in Powershell to securely access the second ssl protected site, and it would send a string back and it would put it at the end of a URL, but have no idea about how to add this into webflow. all in all, trying to send post request with parameter uid equals the login name and the second site return full sign-in url.

Any help or references I could look at?