After you go through all the work to create your beautiful masterpiece, you are going to want to protect it from UV light, dust, dirt, fingerprints, etc. Especially if it is one of those works of art that deserves a more prominent spot than the refrigerator. In this video I talk about spray varnish and fixatif. I use Krylon Workable Fixatif for my pencil drawings and Krylon Spray Varnishes for my paintings.
It is fairly easy to varnish your paintings with spray, but you do need to read the instructions on the container. Watch the temperature, weather & humidity when varnishing and make sure you do it in a well ventilated area. (I personally prefer doing it outside.) This is one I would recommend having adult helpers doing this...or at least being close by to help.
I hope this information helps. As always, please let me know if there is anything I can do to help you in your arting journey!