Registration for the season is via the FACEIT website. In order for the team to sign up for the season, they need to create an account as well as the team on FACEIT.
Registration for the PSL season 5 is available via the following link.
Create a user account via this link.
Once the accounts have been created, the captain can make the team and invite the rest of the players to the team.
More information on PSL season 5 can be found here.
The format and rules can be found here.