Like just make a bunch of blocks that shape out your name? You'd have to adjust your grid scale depending on the level of detail or size of your desired 'signature'. AKA this button :

(REMEMBER TO MAKE IT FUNC_DETAIL)
Or you could make a custom texture with a nice transparent background, so you can have a nice font, but it will be flat of course, then use it as an overlay.
To share your maps you have to compile it first, then host your .bsp file somewhere,
Dropbox is the easiest way to share files with friends.