You have to add them in any of the two menu (I did it in the footer menu and worked well.
When you are editing the menu, click on the right top of the page, Screen options (I am using wordpress in another language so it can be another name), and enable the option css class.
Add the url of your facebook, edit it and put in css class .menufacebook (for example).
Do it whit every social network you want.
Then you have to create classes on style.css or in the editor if you’re using “Easy Custom CSS” like this way:
.menufacebook {
background-image: url( HERE ) !important;
background-repeat: no-repeat !important;
width: 20px;
height:20px;
}
.menufacebook a:hover {
background-image: url(../../uploads/2014/02/facebookh.png) !important;
background-repeat: no-repeat !important;
}
.menuyoutube {
background-image: url(../../uploads/2014/02/youtube.png) !important;
background-repeat: no-repeat !important;
width: 20px;
height:20px;
}
.menuyoutube a:hover {
background-image: url(../../uploads/2014/01/youtubeh.png) !important;
background-repeat: no-repeat !important;
}
Create a png file with the icon you want and upload it to the wordpress. Take the url direction of the icon and paste it where I have put HERE on the css code.
I hope I have been helpful!