For some new shooters, a mentor might not be an option. Maybe your family have never been gun owners. Maybe you grew up or live in an urban environment where shooting and gun ownership is tightly regulated. In any case, you do not know a shooter who you would feel comfortable asking to introduce you to the guns and shooting. Not to worry, the shooting community almost universally welcomes new shooters and provides multiple opportunities for new shooters to be introduced to shooting.
There are a couple of national organizations that provide classes to introduce new shooters to the activity. The National Shooting Sports Foundation (NSSF) provides a First Shots seminar (http://www.nssf.org/firstshots/). This seminar is designed to introduce new shooters to safe gun handling, local rules regulating gun ownership and shooting, and an initial shooting experience. The time is split roughly 50% class room and 50% range time.
The National Rifle Association (NRA) provides a variety of classes and instruction for new shooters (https://firearmtraining.nra.org/student-courses/). Some of the NRA classes, such as the Home Firearm Safety Courses, are non-shooting instructional courses. The first courses that involve range time new shooters should investigate are the Basic Pistol, Basic Rifle and Basic Shotgun. These courses provide both classroom and range time instruction and will teach safe gun handling and proper technique for shooting.
The course you choose would depend on your interest. A hunter would probably choose Basic Rifle since most hunting is done with a rifle, although bird hunting uses a shotgun. If you have an interest in one of the shotgun sports such as Trap, Skeet, or Sporting Clays, then the Basic Shotgun would be the logical choice. If your interest is in Personal or Home defense then the Basic Pistol is probably the correct choice. Of course, there are variations on these as some people hunt or compete with handguns and others prefer to use a shotgun or rifle for Home Defense. If in doubt, talk with the instructor about your interest and what the correct course might be for you.
In addition to the courses offered by the national organizations, there are many local organizations that offer courses. A little research on local gun shops and shooting ranges will usually uncover information about courses in your area appropriate for a beginning shooter. Do not be afraid of just walking in or calling and asking for advice. Most gun shops, gun clubs, and shooting ranges are happy to help new shooters get started on the right foot and happy to help you choose the correct starting point.
One piece of advise is to start with short course to get introduced to shooting and then go back for more if you enjoyed yourself. Not only will you learn more by spreading the learning out over multiple sessions, you will avoid investing a large amount of time and money if you decide that shooting is not for you or your selected the wrong course.