How to finetune with my own dataset?

Thanks for your great work and kindly open source to the public community! I am wondering how to finetune(or maybe other correct terms) this model with my own dataset? I read the training description, but I still have questions:

1. Should I repeat the two stages if I want to tune the model? Can I jump into stage 2 directly with the checkpoint file you provided and my dataset?
2. Need I append my own dataset to dataset folder provided at stage 2, or just replace it?

Thanks in advance!