They result from prolonged and repeated pressure causing chronic changes in the subcutaneous tissues of the perineum. If neglected these will grow and become more painful. Corn plasters placed over the nodule when it is first noticed will generally take the weight off the nodule when you ride, and allow it to settle. If it doesn't settle then stop riding for a few days. These can become a real problem if neglected, so don't ignore them.
Most new cyclist find that their rear end is painful and numb when they first start out.
As long as you have well cared for, clean cycling shorts, this will diminish with training. There are many makes of saddle on the market now which are designed for comfort with gel padding. They differ for men and women, and are well worth the investment. Pay attention to the basic safety rules, make sure that you have the correct clothing and that it is clean and well cared for, set your bike up properly and enjoy your riding. As new research and experience broadens our knowledge, there are changes in training programs and techniques.