how to add a new language to my website

Hi there

My Website content it’s in english. I also want to add the same content of the website but, I would like to make it in romanian. Is there any way for my viewers to have an option to change that? ( i dont know if I made myself clear but like a small icon to change it from english to romanian)

of course I will create the romanian content and added it my website but I really dont know how or where to look.

I hope somebody can help me with my problem ?? thanks