I can't seem to win games, help me improve!

http://na.op.gg/summoner/userName=SenpaiTriggerBot So this is my profile. When I play ekko, I usually farm until I get a kill then I snowball other lanes. If I do badly, I split push towers and try to get occasional picks on the ADC. As Fiora, I split push, during teamfights I usually peel and kill the divers with my ult and go cleanup crew. I'm not sure why but I just can't seem to win. Skarner, I just F + R the ADC and then I stun random people. Any tips?