All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His Slave and Messenger.
Firstly, we say that there is nothing in the Sharee'ah that prevents a man from expressing to a girl his wish to marry her as long as this is done with decency and within the proper limits set by the Sharee'ah. He may say anything that coveys the intended meaning, for instance, "I would like to know what you think about me proposing to marry you" or the like. If he is too shy to do so, he may ask one of his female relatives or her male relatives whom he trusts. The last suggestion is probably the safest choice so as to avoid any potential Fitnah (temptation) or suspicions concerning his intention.
Allaah Knows best.