A website making "business"

so the concept of this is that people are going to pay us to make them websites. Now I'm pretty sure that this isn't legal, so my question is what would we have to do to make it legal? What is the proper procedure for accepting funds?

EDIT: forgot to add this, but my concern is that I'm fourteen, so I wasn't sure if it was legal for me to accept payment for doing work because I'm not sixteen.