Json Post request to a WEB URL

I'm writing here because I'm a little bit desperate and I need a lot of help.

Like the question, I need to make a program in C# taht make a POST request in Json to this URL :" http://95.110.145.175:2020/pickup/login ", I have the id and the password, and then I can make some other call with the GET and take some data.

Any idea? Or maybe something where to start? Because this think is driving me insane! I can pay too if this works.