Yes! You absolutely can use your own art work but please make sure its production ready. We recommend you upload your art work as a High Resolution (150dpi-300dpi) .jpg, .png or .pdf for DTG and a vectored .eps file for screen printing. Our online designer has a built-in resolution checker so make sure you keep and eye on it while uploading & scaling your images.
If you need more information, have additional questions or just can't find the answer to your question here, please submit a support ticket and one of our account managers will be happy to help.