User popularity-meter

I really hope that one of you bright people can point me in the right direction.

I want to create a popularity-meter for people who wants to see what number on a list of names they are. Example: "Your name is the >>4th<< most used names".

They way I see it I'll have to create a place for people to write their first name. Then according to the list it will spit out a number on the list.

However I'm a little confused where I should start. If anyone have an idea where to start or some keywords to search for, feel free to help me! :-)

Best regards Lasse