First, go to https://drive.google.com and Sign in into your Gmail or Google account so that you have the admin privilege to the documents that would upload from your system hard drive.
After signing in to your Google account, the next thing is to upload a PDF file from your system hard drive. On pressing the upload icon from the left side panel a drop down menu will pop out which would consist of two options i.e. File and Folder. Just select “File” and head to the next step.