Blocks are typically not made as-is but rather serve as a basis for other patterns so the instructions below will not go in depth about closures or finishes and are for the default Bella block.
If you do not have someone to help with pinning, you may find it easier to cut the front part in two with seam allowance rather than on a fold and sew the back seam up so that you can pin in the front when trying on.
It is best practice to make a paper pattern from the mock-up if you have made any alterations, as this will allow you to clean up any lines but also means you have a pattern that you can keep producing garments from.