If your Mac is more than three years old, stop and do some research on system requirements before continuing.
This is a two-step process. The first is downloading the update. The second is installing.
Open the App Store.
Select the link to OS X Mavericks.
Select "Free Upgrade."
Select "Install App."
Enter your Apple ID and password.
You will see the download progress under the launch pad.
If you are at work or need to use your computer in the next couple of hours, wait until the end of the day to proceed. The install can take awhile, especially on a busy network.
Select the install icon that appeared in your Dock.
Enter the computer password.
The restart can take awhile, so be patient. This is a good time to leave and come back tomorrow.
If the bar stops progressing, just wait about an hour. It is still working in the background.
Your computer will be slow at first while the changes kick in. It might be a good idea to come to work a little early the day after the install just to give yourself some extra time.
Email Laura Hearnsberger if you have any questions.