so this morning i was wondering around my kitchen when I noticed on eof the onions had sprouted and was kinda moldy. So I decided to plant it. So I got a pot, filled it with soil and put it in.

Which leads to my question... now what? 

Have faith!  That sprouted end wants to live.  Keep it moist and in the sun and wait and see.....

It should send up a flower and make seeds for next year's onions.

And speakin of onions, whenever I use green onions, I cut the end just a little long and plant the rooted end in the garden.  Often it will grow and produce another plant.