I have owned several IH bikes over the years and I can assure you that since IH is going chapter 13 bankruptcy this year (right now) you will not be able to warranty much on any IH bike and they DO MAKE JUNK BIKES TOO! I own two of their higher end models and have owned models made for Dicks sporting goods and they are adequate but not well equipped. Now for your question, It may simply be a matter of loosening the brake calliper bolts and squeezing the brake handle to center the caliper over the rotor and re-tightening the rotor bolts at the same time as you squeeze that handle in and that might just fix your problem! Now if your rotor is bent then you need to true the rotor and since you have to ask how then I would not suggest that you do this yourself. If you paid less than $500 for any IH bike then it is (sorry to say) a cheap model, but cheap can work just fine if you take care of it!