Installing a skylight should be done by a professional. They can recommend the optimal places to put them for the best lighting to suit your needs. Additionally, you want to make sure that the flashing is installed correctly or else your new skylight will leak. Professional skylight installers will take care of the necessary flashing and waterproofing that should be added around the skylight to keep it from leaking. If the skylight is the type that opens, a professional will be able to install it swinging out the right way so as not to disturb other items on your roof.
A skylight professional will tell you what type of skylight you should use to light up the area in question and they will give you a quotation of the work that will be done in a mutually agreed time frame. You should get three quotes before choosing the contractor so you can see if all of the installers are in the right price range with each other. Before you hire the skylight professional, ask to see a list of their professional qualifications.