The first parameter also known as in_parameters basically means that the no. of parameters the current linear layers expects from the previous layer. You can refer to the pytorch docs for better explaination.
I would suggest to take the pytorch 60 minute blitz Deep Learning with PyTorch: A 60 Minute Blitz — PyTorch Tutorials 1.8.1+cu102 documentation 3 .
For your current issue you can refer to this Build the Neural Network — PyTorch Tutorials 1.8.1+cu102 documentation