Hiya John! Welcome to the forum/hobby, I don't think we have any beginners guide here really since everyone comes at it from various levels and with various desires out of it there isn't really a one size fits all way to bring people up to speed. There are broadly speaking 3 or 4 "classes" of quadcopters:
1. toy grade (generally under $100). Usually little or no actual fpv view or video recording quality is limited. WalMart banggood any big box retailer or online retailer will sell these, they have them at bookstores (parrot, holystone, airhogs etc.)
2. Hobby grade generally between $300-1000 used for racing and manual acrobatic flight (steep learning curve but mostly flying for the fun of flying and learning to avoid crashes). Getfpv.com or racedayquads.com for this type of gear.
3. Commercial grade, usually at least $600-$5k. These are stable gps controlled video platforms for carrying relatively high end video gear more safely (dji products basically)
4. Industrial grade, for monitoring or chemical distribution type jobs. Gather data with high end sensors like high res FLIR or LIDAR can be used for mapping or facility management tasks equipment monitoring etc, usually $10k+ hardware+software+support solutions.
Most of us land somewhere in the 1-3 occasionally someone will drop through here talking about 4
In category 2 there are a few popular open source software platforms namely betaflight, emuflight, and iNav that can be flashed onto most of the modern flight controllers. Flight controller is brains of the operation with inertial measurement/gyro/accelerometers to track motion and sends out all the control signals to escs that control motors.