lack of sufficient educational researches in my own country
Well, the Internet has made research studies widely available, so... if you want to do educational research, it should be because you have a PHILOSOPHY OF EDUCATION that you feel strongly about. You should be focused on making a particular change.
So, how do you make a plan for the big contribution you will make as a researcher? You have to start by reading some recent research articles by researchers whose work you admire.
Discuss recent articles, discuss your phil. of education, and discuss your PLAN.
How do you show that you have leadership abilities? I didn't do any community works to prove that.
It's not about what you did. It's about what you are going to do. A leader is a person with a plan.
Go enjoy some recent articles by researchers whom you admire. Let their work inspire your ideas about en.wikipedia.org/wiki/Philosophy_of_education and write a Statement of Purpose that is really about your PURPOSE, your plan.