Step 1.) Enable Upload module from admin (drupal core – optional)
Administer -> Site Building -> Modules
Under Core – optional, mark the upload module.
Step 2.) Set permissions for user to upload and view PDF
Administrator -> User Management -> Permissions
under “upload module”, mark permissions
Step 3.) Add PDF as a permitted file extension
Administer -> Site Configuration -> File uploads
In the field: Default permitted file extensions
add “pdf” to the list.
Now if you create content (e.g., Story), then you can see a “File attachments” dropdown menu . When you attach the file, you can then mark whether or not it should be visible (i.e., to list it in an “attachments” section of the node). Also you can see PDF URL below the file attachmnet dropdown.Copy this PDF URL and paste as link on where you want.
For more help see this video: