Set up Facebook, Twitter and Google login buttons

I need 'login using' buttons setting up for one website. The website already has the login scripts built into the coding and there are already buttons built into the site so just the app id's/secret keys should work. I have dev accounts created at google, facebook and twitter but need the APIs setting up with the url/oauth redirect details etc. I have the app icon image and all the necessary login credentials and all relevant website info.