To change the menu icons you will need to upload new images to the packages >... theme >... images > foodicons folder.

They are specified in order of the menu items. So if your home page will always be first unless you hide it from the navigation block. That will be "first.png", which is an image file. The next will be "second.png", and so forth. There are only six menu items styled do to the construction of this theme. More menu items than six will get to be too long in the navigation area leading to errors.