Wa alaikum Salam waramatullahi wabarakatuhu
Please I want to make it very clear that whatever I say is base on my opinion
If it about been engaged, naturally you must have meet the girl or the boy somewhere before having interest in him/her, so after being interested the best thing to do is to tell your parents first because you must have an open relationship with them, just tell them mum,dad am interested in that man or that woman and as I responsible parents they will do absolute good job by inviting that person that look my so or my daughter has interest in you what did you think about it and you may even meet in the present of your parents and if both of you are okay then Allhamdulillahi.
Even if is on WhatsApp or Facebook just tell him or her that look we are creating a chat group that I will include either my brother or my father, a really relationship that what to become marriage will not refused that
Please try your best, is all for your protection
Jazakumul llahu khayran