Sanjana:
I'm not sure which example you grabbed. If it's one that is intended to be run using the native compiler, then it should work with the configuration you have. Otherwise you may need an additional cross-compiler.
Assuming your toolchain is ok (most of the examples are), in the main folder there will be a make or rake file. If you're looking at a makefile, you can run the tests by running "make" or "make test". If the project has a rakefile, you can instead run "rake" or sometimes "rake test:all". If none of these options work, can you post a link to the project you're working with?
Mark