I would like to add a product but not make it available for sale?

That is not a problem. This is a great way for you to promote your brand even if you aren't selling it online. Make sure you do the following:

After you have uploaded all the information in the add a product section (required), simply set the quantity to zero and put status to Out of Stock in the 'Product Options' section - see image below. This will display your product and information about the product but will not make the product available for sale.