I want to use the Myanmar (Burmese) font on Facebook, how do I do this?
There are certain extensions which allow you to do that. For e.g: Font Changer with Google Web Fonts is a Chrome extension that gives you a choice of 500 fonts to pick from. I am not sure if it allows you to use your own, but guess not as it is based on Google Web Fonts. There is a similar extension for Firefox as well. But it is not only for Facebook but for the web as well.
Also check out this previous thread:
How can I see the Myanmar font on Facebook?
That would not present the font to others, however – only on your end. But if that's what Kogyi wants, fantastic solution.
Do you want other people to see text you write as being in that font? Because if so the only thing you can do is create an image with your text and upload it. Facebook does not allow custom fonts – it's why everyone's text looks the same.