If you are unsure how to follow the instructions for cropping your art work for a call for ArtPop and you don't have a local graphic design resource who can help you. We recommend the paid services of Melody Roberts. She will charge for this service but it is affordable and takes all the worry off of you. firstname.lastname@example.org You will want to supply her with a GREAT high res photo of your art to work with. She can make the suggestions on how to crop for best results in the rectangular or square requirements of the billboards. Please don't wait till the last minute, plan ahead for your call end date.
You will also need to supply her with the call information for your city as each city typically varies a bit in size requirements. Be sure she knows which ArtPop program you are trying to submit to. Thank you and good luck!