nice tutorial on tuning using transformers with pytorch by Chris McCormick here https://mccormickml.com/2019/07/22/BERT-fine-tuning/#4-train-our-classification-model 183.  See also his youtube videos and other posts.
If you want to make a custom model, try this by abhimishra https://github.com/abhimishra91/transformers-tutorials/blob/master/transformers_multi_label_classification.ipynb 129