You can use the social media website to promote your affiliate website on and to generate traffic that can come to your website through your social media marketing efforts on them.
If you don't already have one then it's also a good idea to build an email list of people who are or might be interested in the type of items that you are promoting and then you can start an email campaign to get people to come to your website and hopefully make a purchase on it.
These are two of the better ways to market an affiliate website, there are many though and trial and testing is the best way to see what works best for you.
Cheers, Dean.