How can I repeat the tutorial?
The process JonHick describes in his comment is not a 'workaround', it's the usual process:
To play with friends, go to the Social Club (HOME key on PC by default) and add your friend to your friends list. Now you have two options to play together:
- In the friends list, choose the 'join' option to go to their session
- Start an activity and use the interface there to 'invite from friend list' (then either 'invite all online friends' or 'Select from list of online friends').