While its possible to replace the cover glass you may not like the look. Apple doesn't sell the glass this is a reproduction. It is also Glossy (no anti-reflective glass). If you have the matte finish hi-rez screen you have the best screen in my opinion. The glossy screens are hard on the eyes outside or when you're near a window.
Frankly, I would leave it be. Don't forget if you change the bezel people won't believe you have the better screen if you try to sell your system (lowering its value).
Here is one source: Unibody Macbook Pro Glass Screen Cover Replacement this one has the Black Bezel.
Follow this IFIXIT guide to take the display off: MacBook Pro 15" Unibody Early 2011 Display Replacement. Once you get the display assembly off you'll need to follow this guide MacBook Pro 15" Unibody Late 2008 and Early 2009 LCD Replacement. While not exactly the same model as yours the steps needed to replace the cover glass is the same. Jump to Step 14 and follow it to Step 21. It's very easy to melt the rubber gasket with the heat gun. Getting a replacement will be difficult so be very careful!
Again, this could end up being a very expensive mistake! Make sure you have reviewed things as its very easy to damage things here.