Some people have luck printing a name from their computer and painting it on the canvas, but too often that results in an effect like a stamped canvas. After all the money and time you invest in a canvas, the only way to have the lettering turn out right is hard work, but worth it.
Now you graph the letters onto graph paper. (I like 13 x 13 graphs, but that means more math when you are painting on 18.). Cut the letters out and place them on another piece of graph paper to adjust the spacing between letters. It’s very seldom that you will use the same spacing between letters. Tape the letters in place to hold them steady
I use a textile marker or acrylic paint for my lettering. (NEVER EVER USE PENCIL OR PEN OR A SHARPIE!) I like to use gray because you can stitch over it with almost any color. It’s a good idea to paint the lettering before you start stitching. You can leave the color choice for thread until you have stitched enough of the canvas to have an idea of what will work. Or if all this sounds like too much math, your favorite needlepoint store can paint lettering for you, even matching previously stitched stockings.