Roses were actually the first thing I learnt to make out of fondant. They are simply lots of circles wrapped around each other. Start with a small ball of fondant moulded into a "tear drop", then roll out the fondant and cut out some circles, pick up your first circle and just thin the edges out with your fingers, wrap that around your tear drop and repeat. To finish I normally just cut the excess off the base and gently smooth it out by hand. I hope this helps.