php work

My client owns an event/sports photography business. Where he runs a server onsite, which utilizes Linux and php coding to create an intranet, and that system is duplicated online so you can look at photos. All this coding was done by my nephew, who has now left the business to go back to school, so I need a good PHP programmer to pick up where he left off. We have some tweaks that we want done, like the ability to change our own products and prices. Right now that's buried in the code, and I don't know how to get into it. Not exactly sure how to pay on this whether by the hour or for the job. Please respond with your bid, but also with a per hour charge or per job charge. Thank you. Looking forward to finding someone I can build a relationship with for future projects.