polarizer filter for 18-55 lens

[kimbakaye]

I picked up a Rocketfish 55 mm polarizer filter today for my Canon T3i w/18-55mm lens. I feel really stupid, but how do I attach it to my camera? I assumed I was just going to screw it on to the front but it doesn't do that. It seems to be a very slightly small diameter than my lens. It is a circular glass polarizer and seems to have thread but I can't figure out how to attach it.

Can anyone tell me what I am doing wrong???

[OsmosisStudios]

Your 18-55 lens needs a 58mm filter. Your filter is too small.

This information is listed on the front face of the lens signified by a circle with a line through it, and a number.

[kimbakaye]

Thank you for your reply. Yes, we went back to the store and the guys pointed that out to me I felt REALLY dumb but hey, I learned something new!!