If you lack proper training and expertise, taking on this type of project on your own is not just a terrible idea; it might also be dangerous and end up costing you more money to resolve than if you had hired a professional to perform the work in the first place.
Also, depending on your region and insurance coverage, replacing the breaker box yourself might get you in hot water. For example, the city may need a permit and inspection, making a do-it-yourself project impossible.