Custom Font

Hi.
I would like to know in which file I can add a Google Font, to customize the font used in menus, h1 and others.

This is the code for embed font: ( I do not know in which file I should copy it.)
<style>
@import url(' fonts.googleapis.com/css?family=Josefin+Sans ');
</style>

Example of my custom.css

.menu-dropdown a.level1, .menu-dropdown span.level1 {
font-family: "Josefin Sans";
font-size: 16px;
}
h1 {
font-family: "Josefin Sans";
font-size: 13px;
line-height: 10px;
text-transform: none;

I hope can you help me.
Kind regards.

Add this code at the top of your css/custom.css

@import url('fonts.googleapis.com/css?family=Josefin+Sans');