Flower nails are metal - domed top and a thin stem - similar idea to a mushroom.
You put a dab of royal icing or buttercream, or Bluetack (do you have that in the States?) on to the top of the dome, stick a small square of waxed paper - wax side up, and then you pipe either with buttercream or royal icing on the waxed paper, either a rose/leaf/daisy or whatever you wish to do. remove the waxed paper(s) and allow to dry, then the piped items can be used on your cake.
Hope this helps.
smque2 
Don't feel bad for asking the question. My husband recently admited that he had never quite understood how they were used until he was in the grocery store this spring and saw someone making a flower in the bakery. He had thought that the flower was done on the spike and the flat part was used to set it on the table. 
Shows how much attention he pays me. 
They also make great heating cores instead of those huge heating cores Wilton sells. Just put them "head" first in the bottom of the pan and wola, an instant heating core. Make sure to prepare them just like you do the pan.
For the 14 x 2, yes. For the 8" x 3" , you could but if you don't use one, lower your oven temperature by about 25 degrees for the 3" cake so it won't bake too fast or get too brown on you.
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