Id like to get the achievement, but i have nothing to advertise. Could i just make a billboard sending out a positive message or greeting?

i did that pretty recently; it took a day or so to be approved but my billboard is still floating around, telling people to have a nice day p: you don't even have to make it link to anything.

you could advertise for your favorite item, also -- i remember a few months ago there were a pair of billboards advertising for that linked to the horchata shop search page and i thought that was cute, haha

Sounds fantastic haha ill keep this in mind. I may be rusty on my coding but my graphics game is strong! Where do you see billboards anyway?

wherever you see the regular ads, generally at the top of the page unless you have custom css that moved it (if you've got some kind of ad block on, look for "remove this ad").