Do all my players need to register with Gotsport.com
No, you just need to have, First Name, Last Name, DOB, Gender and email address. You can if you wish, create a Gotsport.com accout for yuor players if you wish.
How do I add guest players
The same way you add players. Do a search wthe their first and last name and date of birth. If they have a Gotsport account, then they will pop up and you can select them. If not, It will allow you to imput thier information for your roster