She would either have to transfer her existing real-life skills (i.e. selling any type of artistic creations, freelance writing, marketing, etc) to online or pick up computer-specific skills (programming, website design, graphic design, etc). Selling stuff on ebay or etsy, for instance, requires capital and/or artistic skill to have inventory to begin with. And earning a lot of money may not be a realistic goal - even earning supplementary income just online may not be easy.
If she has existing skills, I would check out something like Fiverr or look on Craigslist for odd jobs, or at least to get an idea of what people are doing for online jobs.
Not that I'm an expert or anything. I don't know that many people who make money online just like that, though, it's usually small businesses who use the internet as a virtual storefront, or otherwise are experts in a computer related field.