Tips on loosing weight.........?

Okay so i am a 16 year old girl and i am 5'7" and for some reason i haven't been able to break the weight of 136 pounds for quite some time now. I am pretty active. I play basketball practically all year round. I have also recently started to do zumba. I do it for twenty minutes four times a week at my house and once a week I go to an hour long zumba class. However, sometimes my eating habits aren't always the greatest. I mean they aren't horrible but i admit they could be better. I just have issues sticking to a strick meal plan and I tend to grab whatever is easiest for me to eat while I'm home especially during the summer. Also, I work at an ice cream stand so there is that temptation to eat all that junk food while i am working there. So, I just need tips on how to lose weight or how to stick to a healthier diet and how to resist the temptations of junk food. My goal weight would be probably around 120 pounds. I just need some help to get there. Thank you all so much!!!