The Nook supports a wide range of e-book formats, including ePub, BBeB, Adobe PDF, XLS, DOC, PPT, PPS, TXT, DOCM, XLSM, PPTM, PPSX, PPSM, DOCX, XLSX, PPTX, JPG, GIF, PNG, BMP, MP3, AAC and MP4 formats.
You may also download the image as a JPG or PDF file.
You'll find games, invitations and cards (many of which are in jpg image format that can be personalized), clipart, and lots of other great ideas.
It's always important to note that the file is in jpeg, jpg or gif format.
Make sure the pom pom image is in JPG or GIF format.