Where can I take my 2011 MacBook Pro to get a new hard drive?

It is very hard to effective answer "where" questions with no idea of your approximate location. These are international English language forums and it does you little good if we recommend an vendor of service provider who cannot ship or work where you are.

That said, the short answer is that most people do that at home. 2011 MacBook pros are easy to open and service with no special training. We can provide links to video instructions.

If you don't feel comfortable doing this yourself or following step by step videos, the best thing to do is an Internet search to see where you can take it. That will give you a list of certified repair centers for Apple.