Our design tool accepts jpegs, pngs, eps, gif and tif files. You want to make sure your file is at least 300dpi with transparency at the desired print size for the best possible print result.
To save your print ready images in Photoshop or Paint, go to File > Save As > PNG. In Illustrator or Draw, you must export your image, go to File > Export > PNG.
If this all sounds like gibberish, then here is a really simple way of checking your artwork.
Open your print file on your computer screen. Grow it to roughly the size you would like it printed. If your image is looking a bit blurry or pixelated, this is how it is going to print. If you are happy with this, fab! Go ahead and upload your design.
If you were wanting it to look a little crisper, we recommend finding another file.