“Reselling” is when you buy merchandise, then re-sell it online. You need to find a source / sources of inexpensive goods, buy some, then list them on eBay or Amazon.
Two bloggers that I read are having series of posts on how to get into reselling.
Miles to Memories is just starting his series.
Doctor of Credit is up to post #6 on reselling.
Both blogs are worth reading if you foresee using reselling as a way to meet minimum spends, or to actually make an income.