Here's 3 ways to get words onto a canvas. Have fun with your project! http://paintspirationart.com/diy-3-easy-ways-to-paint-quotes-on-canvas
You can print the words you want on paper and cut them out. Put them on canvas and trace around them and then paint them. You can also buy them as decals on the internet. Or if you are looking for custom words there are many shops on Etsy that will do it for you or make the decals for you.
You can paint on them or use paint pens to write.