There are videos on YouTube on how to do it, but if you aren't comfortable, for sure take it to a store. If you go to a store, they may want to put 11s on, which is the most common gauge for acoustic, which will still be fine, but they are harder for newbie fingers to adapt to. That's why I keep a guitar strung with 9s for beginners who want to try guitar.
This year the diet is definitely gonna stick!