Ahead of kills

I'm so tired of loosing so manny games that we are ahead of kills. I know it's important to have turrets down but last game even a team who wasn't groupin up won over us though we had more kills and was pickin them of all the time, I really don't know how to win a game. The only thing I'm good at is getting kills and try to take down turrets to secure the win but we still loose most of the game I carry.

Tips pls. :)