That's completely up to you :3 You could choose to review something that was created around the theme of celebrations (eg a wedding themed movie or a party song), you could talk about what the work should be celebrated, you could talk about how the work could be used as part of a celebration, or you could do something much deeper or much more obvious - it's entirely up to you based on how you think the work best fits the theme. :)
Thanks. One more question haha, if I can ask, how exactly are we supposed to incorporate the theme celebration? As in is it supposed to be a prevailing topic throughout the review or is it something we can make subtle?
If the review is well presented then it'll certainly give a better impression whilst reading it, but the content of the review is much more important so as long as it's well written the formatting shouldn't matter too much :)