Do you have experience writing web apps? If you remember the URLs for these tools, just sign up for trial accounts or something and try to reverse engineer how they work. I find flowcharts useful in nailing down the exact user flow, and then just use your CS/SWE knowledge to build a suitable backend that satisfies the constraints. You don't want to turn away your friend by bombarding her with endless questions, but you definitely have a place to start with what you've already described