If you're new to magick, it's not the best idea to start off with a spell. Read up on how magick works first. Focus on studying for a while before attempting to cast a spell.
If you have been studying for a while, it's almost always best to write your own spell. It tends to be more effective, since you know what every word in the incantation means (symbolically or otherwise), you can choose supplies based on what's readily available to you, etc.