It appears you get coins by responding to posts, uploading charts that are not already on the site, creating your own videos. I was able to find this information on the homepage.
There are also tasks to do hourly. It really adds up. And Every beginning of the week is a new youtube task that you dont require giving pindiy your access to google. Because Google blocks 2 of the youtube tasks but not the once weekly one.
And Comment. or might I say interact on here. Helps you level as well.
chekccard
upgrade card
set top card
replt card
Noisy card
Colorizer
Jack