How can i go from a button to a especific part off de homepage

Hi, i've got an button on my home page and i want that when i make clik on it, the pages slides down until muy contact-info part of the home page, but i'm not able to do this, instead it go to another page. i would like to now in wich .php should i add the anchor, so that i can text in the button link #(anchor-name) and the qhen i click on it i go to this part off the home page.