Will I gain weight taking Creatine and Optimum Nutrition Serious Mass?

In my previous questions, I was deciding whether to get these and try them. Well I did. Ive always had a hard time gaining weight, but if I take creatine with ON Serious Mass. Will I gain weight? Of course, ill workout and follow the instructions on the bottles. Nothing else works, and I heard these are 2 of the best things out there to help you gain weight....just wondering if you think I will?