How do you patent invention idea without help of patent attorney?

My aquaintance, mechanical ingineer, has told me that the possibility of self patenting does exist but I do not know steps. He told me that it is enough to make serch for invention idea purity and to registrate it with site USPTO.Gov, or, or I did not try to do so yet. I wait if anibody who has experience to self patent idea will add to my almost answer.