First of all, You have to register an account in shutterstock.
After the successful registration, you could upload your artwork, illustration, vectors, photos or videos to shutterstock.
Every submitted items will be reviewed by shutterstock. After the review process, only approved items will be shown in your portfolio.
For not approved items, you could revise the content according to the reason provided by shutterstock. Subsequently, you could upload the revised items again.
Finally, Shutterstock is a good place for designers to start your journey and here is my shop. Please take a look at it! Thanks
https://www.shutterstock.com/g/cutequokkahappiness