Shape of input a sentence regression task

Hi, I want to do a sentence regression task. I have a text corpus comprising of sentences that there is a score for each of the sentences in the text. I want to predict the scores.

I want to use RNNs. The sentences in the text have different lengths. I don’t know how can I handle them? I also want to know that what is shape and structure of the input to RNN?

It’s the first experience in Pytorch and deep learning. thanks.