Here are some good videos explaining the basics.
https://youtu.be/coULRRhZsUw - this one uses a different program but the steps can all be replicated on vcarve.
https://youtu.be/-AxJ6DHqa-I - fast forward to the last project in the video. He does mount the wood vertically so that the bit can create nice square joints. You’d need to create a jig on the far end of our cnc to hold your wood vertically.
There is also a dovetail box gadget you can download from vcarve that will do a lot of the heavy lifting for you. I think you just have to go through and add some fillets to the file. You can select dovetail or box joints.