This gives you a Server Token, which is only useful to give you a higher request rate for non user API requests.
You take the code and perform step three of the oAuth dance, you exchange the code for an access token, as documented:
3) On your server, get an access token by making this request:
POST https://id.twitch.tv/oauth2/token
?client_id=<your client ID>
&client_secret=<your client secret>
&code=<authorization code received above>
&grant_type=authorization_code
&redirect_uri=<your registered redirect URI>
After obtainin an access token via step 3 of hte oAuth dance you can make an authenticated request to
as documented:
Thats entirely up to you and how you wish to handle oAuth/third party service logins/session management.