Two issues with the group I created

[SfNinerFan]

My first issue is I created a group call San Francisco 49ers Fan about 2 months and I want to edit it to say San Francisco 49ers Fans but it says there is already a group with that name. I searched and there is no group with that name. Second issue is how do I get people to join my group? There is a group called the San Francisco Giants Fans that was created 5 months ago and they already have 966 members. How do I get people to join my group and how do I edit my group name?

Thanks!