First, choose a few words that describe the picture: poise, shadow, cheerful. Using Thesaurus.com, find several new words that have similar meanings:
POISE: aplomb, deft, equanimity, serenity, tranquility
SHADOW: penumbra, obscurity, eclipse (v.), veil (v.), obfuscate, murky
CHEERFUL: winsome, effervescent, jaunty, vivacious, sanguine
(Test makers love to throw in verbs typically used as nouns. For example: eclipse and veil, above.)
Now you can describe the picture in several sentences, making use of your extended vocabulary!
1. The vivacious dancer springs from the obscurity of the shadows with one deft leap.
2. The serenity of the murky corners of the dance studio was soon plucked away by the sanguine scuttling of a thousand toe shoes.