Tell your teacher!!! As fast as you can. Let your teacher know that what you are reading makes no sense to you. That way, your teacher will realize that you are trying. Your teacher may have other ways for you understand what you are reading. He or she may offer more help after school, a tutor, a movie, a website, etc. As long as you ask for help and try, you are half way to getting this frustration fixed.
The suggestion above, by krausel, is excellent as well. Try everything!
Hope that helps!
Try reading the passages out loud to yourself, or have someone else read the passages out loud to you. Sometimes hearing the words will help them make more sense. You can download many books onto an ipod or mp3 player from a website called Audible or from itunes. You can also check your local public library for books on CD.