Hi Kim, congratulations on starting up your business!
We’re pretty lucky that we now live in an age where there are lots of template-based website builders available where you can build your website without needing coding knowledge. This is often a good place to start. It will depend on what your business is but based on your mention of selling artworks I suggest you investigate Squarespace (which is well suited to showcasing portfolios and has ecommerce functionality) or Shopify which is an excellent ecommerce platfrom and integrates beautifully with Instagram and Facebook. Shopfiy is usually the go-to for ecommerce start ups especially if you have fairly standard requirements.
In terms of Facebook and Instagram I suggest you look at the Facebook Blueprint courses here: https://www.facebook.com/business/learn?ref=ens_rdr These are a great way to get more confident with the platforms and start exploring some more advanced tips and tricks. Once you’re up annd running, make sure you add the Facebook pixel to your website and integrate your website into Facebook Shop so you can sell across all three platforms.
Good old YouTube is a fantastic resource to walk you through step-by-step how to do these tasks.