My Blog is Broken

Several people have mentioned to me that my blog is broken. Well, actually the design of the blog. I've seen blogs that I couldn't read, with overlaping sidebars or text so big or little or overlapping that you couldn't read it. I'm so ignorant about this that I thought they just didn't know how to set it up! But I now understand it has to do with the program being used to view the template. Anyway .... It looks fine to me. But I'm not using Fire Fox. I have no earthly idea how to fix it. Can anyone help? I've thought of switching to Fire Fox or Mozilla. But if I do, does that mean people viewing with IE won't be able to view it? Thanks for the feedback and thanks in advance for any help!