Need help for create a really simple app

Hi, i don’t know were to start, i would like to know if it’s possible to do what i need. Here it is : A page with button and a gauge. When one person clic on the button the gauge is at 1/100 for every user on the site (for like 2 sec) if they are two to press it then 2/100 ect…

And i would like to know what tutorials should i watch ?

(sorry for my bad english)
Thank you for your help