The parts in the VFlash are built upside down on a build platform, along with requisite support structures. Once the new part has been built, it will need to be cleaned off the build platform with caution and the support structures removed (typically with flush cutter pliers).
This process is very time consuming and has a bit of a learning curve. The part that comes out will be better as long as you spend more time on it. There are endless possibilities on what to make 3D in this world and this is one of the methods. It is challenging but do not give up! There are many resources on each of the programs and it is highly recommended that you do a little research before beginning that next big build file.