Guys just a question about lifting weights?

if I increase the repetition it will tone my muscles, right??, if I increase the weight what will happen?? and would it be effective to increase the weight by 125% of what I can lift to make myself buff?? I'm 16 please tell me if there's going to be some problems if I did increase the weight of what I can lift because a guy told me I might have hernia if I lift heavy weights.