If you want to submit your kids drawing, you can use the following platforms. 

1. Facebook:You can share your kid's drawing on Facebook. There are 2.85 billion monthly active users on Facebook.
It means, there are many people on Facebook to see and like you kids drawing

2. Instagram:You can share your kid's painting (Drawing) on Instagram. There are roughly one billion monthly active users on Instagram. It means there too are many people to see your kids drawing

3. YouTube:You can share some videos of your kids drawing on a YouTube channel. There are 2.29 billion users on YouTube. 

4. Pintrest:You can share your kids painting on pintrest too. There are 454 million monthly active users on pintrest

These were some platforms where you can share your kids drawing