These are the steps to know how to edit a PDF file using Google Docs.

 Sign in with your Google account to Google Drive. On the top left, click New.
 Choose Upload File.
 Find the PDF file to edit and select Open in the document window. After completing the upload, click Recent to find the PDF that you are just uploading.
 Right-click the name of the PDF file to open with > Google Docs.
 There is a new and editable Docs format.