Black grout does exist. Try builders merchants rather than DIY stores. If you cannot get it locally you can mix mortar colouring powder with grey grout to get black. This is also available from builders merchants but mix it into the grout powder when dry. We have never seen pre-mixed black grout so you will need to mix the powder yourself.
DIY how to tutorial projects and guides - Did you know we have a DIY Projects section? Well, if no, then we certainly do! Within this area of our site have literally hundreds of how-to guides and tutorials that cover a huge range of home improvement tasks. Each page also comes with pictures and a video to make completing those jobs even easier!