I assume the QS4s came with the wall-mount brackets, right? How you attach them to the wall depends on what material your wall is made out of.
If it's drywall and you are NOT mounting it to a stud, then you need to get some drywall anchors. You can find these at any harware store and they usually come with the appropriate screws.
If your wall is drywall and you WILL be mounting to a stud, then you just need wood screws, at least 1.5" long.
If your wall is masonry, then hardware stores also carry masonry anchors.
