I always found when setting large goals it helps to also have short term and mid term goals in addition to the long term goals. Also it is important to write them down and read them often if not daily. Also if you really want to be serious about achieving goals you should have a real burning desire to do so.
In your case you could write down a short term goal (and date) of when you want to learn enough skills to actually start the business.
You can then set a short to mid term goal as to when you intend to become the largest in your town.
You then could set a long term goal of becoming the largest your state, and even longer one of largest in your country, and then your farthest out goal of becoming the largest in the world.
As time goes on and you proceed in your short term goals don't be afraid to adjust and modify your longer term goals as you learn more about what you like, desire and better understand what your strengths and weaknesses are.
Your short term goals should be very specific with a plan. Your longer term plans less exact in details but rather a direction you intend to head. Kind of like carefully watching where you walk when hiking so you don't stumble, while always heading towards the large mountain far off in front of you. If you spent too much time just thinking about climbing the mountain peak and don't watch where you step, you might trip over something right in front of you. Along the way you might also discover that when you had dipped down into a valley, you discovered the most beautiful lake and decide you would be much happier to just stay there instead of your original goal of climbing to the mountain peak.
I wish you well.