The solution is to put the fonts folder into the stylesheet directory, and then write:
@font-face{
font-family: Airplanes;
src: url('fonts/airplanes/airplanes_in_the_night_sky-webfont.eot');
src: url('fonts/airplanes/airplanes_in_the_night_sky-webfont.eot?#iefix') format('embedded-opentype'),
url('fonts/airplanes/airplanes_in_the_night_sky-webfont.woff') format('woff'),
url('fonts/airplanes/airplanes_in_the_night_sky-webfont.ttf') format('truetype'),
url('fonts/airplanes/airplanes_in_the_night_sky-webfont.svg#airplanes_in_the_night_skyRg') format('svg');
font-weight: normal;
font-style: normal;
}
The images folder can be at the same level than the stylesheet one's, and then you should write:
background: url('myImage.png');