So I bought a Decor Pass and it's supposed to work with holiday decor but I can't find any holiday decor at all to use it on.

There's no holiday currently.. Eve will announce on the news that there's holiday decor on the news page~ when she announces that, then in barter there will be holiday decor. Same with events, except it'll be under Event Shop

There isn't any holiday decor this month. Next month there will be some holiday decor. :)

Thank you both for your answers, I'm going to wait until the Halloween event then. :)