In the DocuGen Sign item view, expand the "Document" accordion:

Upload file

Use this option iI the document that will be need to be signed will not change from one signer to another. For example, your document might be a standard contract (e.g., a non-disclosure agreement) where the contents are the same every time. 

Once you select "Upload file", you will see a button to upload your document. You can upload PDF or .docx documents.

Catch from a Files column

Use this option if the contents of your document will change from one signer to another. For example, you might want to send a sales order or a lease agreement for signature. These documents will have different contents depending on the situation. 

Once you select "Catch from a Files column", you will need to select the Files column to use from the dropdown.

You are now ready to define the signers.