Define the outermost edge of the rose now, you should be able to see its shape. The petals on the outside are the biggest, and they fold around each other, coming out from the stem.
Tip: You don’t have to draw in the stem, but if you add a small part, it just helps to certify that it is a rose! You can add in some thorns too, they are slightly hooked, and remember, you can always search for some reference photos on the internet to find out how roses look. Remember not to go over the top with the thorns, they don’t have that many, so don’t turn your rose into a cactus!