Service getting an error while building the source code

Hi,
i have downloaded android (jelly bean )source code, while building i have gone through this command
.build/envsetup.sh
then i got the following error

No command '.build' found, did you mean:
Command 'sbuild' from package 'sbuild' (universe)
Command 'pbuild' from package 'pbuilder-scripts' (universe)
Command 'xbuild' from package 'mono-xbuild' (main)
.build: command not found

i am not getting how to build my source code
i wan your help to complete my work
i will be very thank ful to you ....


thanks in advance