I need to download nfs-common(package that need for NFS) on my Yocto system, but I don't understand how to do that.
I try apt-get and yum but that doesn't work.
Well, if your building your own system, then you need to add the required packages to your image. (I.e. add them to IMAGE_INSTALL).
If you're just running a pre-generated image, you could very well find it a lot harder...
You need to find the answer to the following questions:
Do you have any package manager at all installed?
If you have; does your provider have any repositories that you can add? Otherwise you'll likely need to build the package yourself and transfer the required package (rpm, ipk, or deb) to your image manually.
If you don't have any package manager installed, you could still build a package and try to move and install all the files manually; though it would be a lot easier (and better for the future) to build your own image in that case.
As it was a Freescale system, I'd guess that you can find more information about the actual BSP at FSL Community BSP