how can i watch netflix?

yes. You'll need the silverlight. Go to the netflix website and it will walk you through it.

Here, Try this...

Original Link: https://support.netflix.com/en/node/2086

Follow the steps below to install Microsoft Silverlight:

1. Click on any title to play.
2. Click Install Now.
3. Click Save File.
4. Double-click Silverlight.dmg in Downloads.
   • For Safari, the Downloads menu is in the upper right-hand corner of the browser.
   • For Firefox, Downloads is a separate window located in the Dock.
   • Note: If you have trouble locating the download folder, press Command + J to bring up the Downloads section in your browser.
5. Right-click or hold Control on your keyboard and click on Silverlight.pkg.
6. Click Open on the pop-up menu.
7. Click Open on the prompt that says "Silverlight.pkg" is not from the Mac App Store. Are you sure you want to open it? Opening "Silverlight.pkg" will always allow it to run on this Mac.
8. Follow the prompts to complete installation.

Yosemite + Chrome is all you need

Firefox did not work. Period. johngilberttyler got it right! I have El Capitan and Chrome worked just great!!!!