Write an email to the editors at mat-szerk[at]komal.hu (or fiz-szerk[at]komal.hu or inf-szerk[at]komal.hu depending on subject) with the problem statement, solution, and with your name and city/country of residence.
I have heard about Komal since I was in secondary school. It's great now I can find its content online. I have browsed the website but I couldn't find the information for author to propose a problem for Komal.