No, you do not have to file the return yourself. The Your e-PIT service will prepare a PIT-37 return for you. If you do nothing, the return will be automatically accepted by the deadline (30 April).
However, if you wish, you can file the return yourself. To do this, log in to the Your e-PIT service, then, for example, complete the return with any available tax reliefs and deductions, and accept it before 30 April.