First, try to understand your reason for taking up muscle building. Some want to build up muscle mass, others want to be slim or build their core muscles. Muscles also useful to become stronger and more efficient at routine tasks needing physical energy.
In a journal or diary jot down why you want to take up this training program. Write down your goals. Where do you want to be a few months down the line and also a few years from now. Goals and targets help you by guiding you on a path. Not knowing why or what you want to do with bodybuilding will lead you nowhere. Be realistic in setting up your goals.