how to make custom forms plugins for registered users only

hello,
i don’t know this topic might covered else where. but i am trying to find step by step simply tutorial. to make a plugin where i can add a new page to site. and in that page i put some form. and only registered user can access that.

i managed to make plugin at admin side. but not able to find the tutorial to make a form at front end of website. for registered user only.

please give me some link for it.

my core issues are

1. how can i display custom coded php form in only one page in front end.
2. how can i make that page ristricted for registered user only.
3. how can i customize the registration form to add custom fields.

Thanks in advance.