This process varies a little bit depending on which version of Windows you're running.
If you are running Windows XP this update is super urgent for you, that's why I listed it first. You need to go to:
- Start > All Programs > Windows Update.
- Click "Scan for Updates"
- Click "Install Now"
- Allow the updates to install
- Restart your computer.
- Now that you've got those all up to date, you have to manually install the latest patches. Go to this link: Microsoft Update
- Scroll down to "Windows XP" and click each of the numbered links and download the update.
- Open the files that download and run the update packages.
- Restart your computer after installing each package.
If you are running any other version of Windows (be it Vista, 7, 8, 8.1, or 10,) the process is a bit easier.
- Click your Start menu (or hit the start key, pictured below)
- Type "Windows update"
- Click "Windows update" when the search results are displayed.
- Click "Check for Updates"
- If updates are available you will see "Install Updates"
- Click "Install Updates"
- You may have to wait for the updates to download then install. Either way it may be a few minutes. Or hours. Now's a good time to go grab a cup of coffee or see a movie.
- Once the updates have installed it should tell you to restart. Restart your computer.
- Boom. You're up to date.