No. The Book of Mormon does not replace the Bible at all, rather, it testifies of Jesus Christ, and of the truths that are in the Bible. Mormons actually carry the Book of Mormon and the Bible when they go to church, and they study from both on a regular basis.
The Book of Mormon is a record of an ancient people, translated in the late 1800’s. It covers about 1000 of history, starting about 600BC in Jerusalem.
If you’re interested in seeing for yourself what the Book Of Mormon is all about, you can read it online, or get a free copy delivered. The links are below. Let me know if you have any questions about the Book of Mormon, or would like some suggestions on good parts to read.
Free Book Of Mormon: http://www.mormon.org/bookofmormon
Read Book Of Mormon Online: http://scriptures.lds.org/bm/contents