- Add new post.
- Click "Add Media" button.
- Using the file selection thing, select your PDF and click the upload button.
- After it uploads, you'll have this new section that shows a Title, Caption, Description, and Link URL. Fill in any of the fields the way you want.
- Click "File URL".
- Click "Insert into Post".
Fill in Title field with what you want for the link text because EVEN if you selected the text in the post before uploading, it will be overwritten by what I put in Title field.
For the Link URL field you need to select "File URL" for the link to open the PDF file.