That depends - what app do you want to use to view the PDF file?
You can email the PDF to yourself and view it in Mail, and then choose to open it in another app from there.
If you want to use iBooks, this Apple Support document will help.
With apps like Documents 5 from Readle you can connect your iPad to the computer through iTunes and transfer it in that fashion.
With apps like Goodreader, you can wifi tether your iPad to the MacBook and transfer files in that fashion.
With both Documents 5 and Goodreader (and many, many other apps) you can save the file to a cloud storage service (Dropbox, Google drive, Box, etc.) and download the file directly from the cloud service to the iPad within the app.
In the end, the means of transfer depends on the app.