Hey I'm a Canadian Content Creator. Follow the procedures through the "contact us" link and prepare for about 6-8 correspondence emails with a Roll20 representative. Treat the letter similar to a cover letter including relevant portfolio links and perhaps a few sample image attachments. It might take a month to reach an agent after an automated reply of reception. My experience with their staff was pretty good/professional. You have to be exact (no mistakes) with any deliverables they request and read the emails they send twice over in case you need to send a notice when your first art pack is ready. There will be a virtual signing of a merchant agreement and a W8ben which allows you to operate with a tax exemption. I recommend, for your Canadian taxes, to monitor your payout records from roll20 via your affiliated payout app (probably paypal). Unfortunately, the record will be a bit odd as your exact payout is converted from USD to CAD on the fluctuating conversion rate. It's very exciting and somewhat nerve racking :P For further research, Roll20 has pages on becoming a marketplace creator which discusses the basics of creating art packs, the resolution averages they operate in for pngs, ect. The forums, internal and external of Roll20 have general discussions regarding preferred dimensions for tokens and such. I like 280x280pixels as it converts to 70 x 4 or a 2 by 2 grid square. Stuff like that to avoid snags. Good luck.