How to change my page in web such as dashboard?

I'd like to change only body not all including nav, sidebar in html file when I click the menu in sidebar.

for example, when I click the Coding Convention menu in sidebar, It must be changed from index.html to test.html. and index.html includes nav, sidebar but test.html not.. so There is ViewPager or frame in android, I wanna develop this function in web.

plz, help me.

This is my web smaple image