First and Foremost, apply your base.
I've chosen two colours -which you can find below- with which i've done a colourful french manucure.
Then I've taken a special nail art brush (but you can use a black nail striper) and i've dipped it in some black nail polish, so I could firstly draw a line, and then do two triangles to make the bow.
Last but not least, wait until it is really really dry (1h) and apply your favourite top coat on top of it ! You're done !