Really dumb, but how do i find out what model my car is? (like si, ct, xl)?

i have a 2011 honda civic coupe, and the manual says "all models except si take regular fuel" but i thought my dad said it took regular when we got it, so i've been putting regular fuel in it, where as it says si models take premium. there haven't been any problems with the car or anything, but you know.. it should have the proper fuel. i looked through all the papers and one said "honda/ civic / coupe ex / 2011" but i didnt think they even made ex coupe's? i'm really blonde on the inside, so please bear with me. :(