I am starting learning in performance testing and tried to search about free open websites to perform performance in it. Can any one give me URLs for websites like this?
Public websites do not want you to run your performance test against them. In fact, there is a name for that situation: it's called an attack, and you could get into legal trouble for it.
If you want to run a performance test, set up your own website. (For your purposes, you can probably run the web server on the same machine as your test code.)