I assume you will be working in an environment in which you succeeded to build hello-world.
./configure --host=arm-poky-linux-gnueabi --prefix=/usrWith this line you indicate that you are going to build for arm and that the root of the resulting files should go in the /usr folder.
3) Creating the installables
make install DESTDIR=/home/user/mylibThis creates the stuff that is normally needed to install a library (.so .a) and to use it during building (.h).
tar -czf mylib.tar.gz usr
4) installing in build environment
sudo tar -xzvf mylib.tar.gz -C /usr/local/poky/eabi-glibc/arm/arm-poky-linux-gnueabi/This copies the libraries and header files into the correct place of the development environment.
You should now be able to use the library for porting other apps.
This ofcourse only works for libabries that come with a configure script.