There is a lot of way to promote your website or online shopping site or product site by using various social media site.
Suppose, you have an website named contentmart. This website is a marketplace and opened a great opportunity for various content writer and copy writer.
Now, what kind of step you need to take to promote this site? If I talk about facebook, you can open a page named by your website. You can also link that page with your website. Than you can post various content which is related with your website and which will represent your work.
You can than also promote your website by boosting and reach to more people you can imagine.