1. Close all programs except your browser.
2. Make sure you're online.
3. Go to Windows Update.
4. Click "Product updates."
5. Accept the system evaluation by clicking Yes.
6. You'll see both critical and optional updates. Click the Critical Update box.
7. Click the gray Download box in the upper right corner.
8. Click "Start download."
9. Accept any other options.
10. Once all components are downloaded, restart your computer.
11. Update your browser monthly or whenever a big virus hits.

These instructions may vary depending on your operating system. But the process is similar in all versions of Windows.