Hi Sowjanya
Rational rose is an object oriented case tool for designing applications using UML.
http://www.tek-tips.com/viewthread.cfm?qid=1140&page=6 You can visit the above link to know a bit of that.There are quite a few books in the market such as follows:
1. Mastering UML with Rational rose by Boggs Wendy
2. Rational rose and UML by Bormann Alf
You could also search for a good book through javaranch...
Best Regards
kris