I found an easier way to do it in Premiere instead
I don't know what kind of tutorials you've been watching, but the question you're asking is the kind of stuff that's covered early in the class on the first day of AE 101.
I bet you're looking to jump right to the fun stuff, which in 95% of cases leads to After Effects failure. I STRONGLY recommend that you resist the temptation to think, "Hey, how tough can this stuff be, anyway?" and spend some quality time here:
You need to know the basics, or you're gonna get lost. I have five whole American bucks that say so. Blow the basics off at your peril.
I already said that I'm just learning After Effects, and I also already said I found an easier solution, but thanks for having 0 respect for people trying to learn a new program.
Likewise, thanks for having 0 respect for someone who's been using the application for more than 20 years and knows the pitfalls.
You don't know the basics, pal, and with this application, you gotta walk before you run.
Frame rates are controlled in the composition settings. Frame rates for imported image sequences are controlled in the file interpolation settings. The default frame rate for importing image sequences is controlled by the preferences. Holding down the control/command key and clicking the timeline indicator will switch between frames and timecode.
Judging by your post you walked four times around the barn instead of spending a couple of minutes reading the help files.