We have a Spotify premium family account with 4 users. 2 of us are in some way connected, which means that we cant listen to music at the same time... If I listen to spotify it´s no problem, but when he starts to listen my music stops.
It sounds like you are trying to use the same account to listen at the same time. You all need your own account, I'm guessing your account would be the primary (owner) account. What I would recommend is that each person creates their own account over at https://www.spotify.com/signup/ (you can either do this with an email address or through a FB account). Once they have done this you as the owner can send invites to other members which allows them to access premium.
Check out this handy guide for further instructions on how to send invites