Welcome to MM (Model Mayhem) and I hope you enjoy your stay here. Be sure to post around here in the forums to get to know every one of us and to work with in the future.
Since you are a bit confused of what this website is all about, it's a networking for photographers and models along with retoucher, makeup artist and among others to assist photographers and models but it is network mainly for photographers and models.
This website is one of largest photographers and models networking where you can communicate with other photographers and models and as well search for photographers or models to work with in your area or in the areas that you may be traveling to or pay their traveling expense to your area for your work with others such as photographers or models. Also to show your portfolio publicly to all photographers and models so that they get the ideas of what your work is all about and what you want so to see if it'd suit them to work with you.
As goes for the forums that's to enjoy your time talking with every photographers like myself and others and as well beautiful models, and to ask for feedback on your works that you had done, and also advices for your work with camera and gears if you are photographer or fashion related and makeup, posing and among others if you are models. Nonetheless, Model Mayhem is network for all photographers and models.
Hope that clear up a bit for you.