FreeBsd makes keeping your system up-to-date relatively easy using a utility called freebsd-update.
to download all updates
To install the downloaded updates
When it comes time to upgrade to a new major version of FreeBSD you will need to use upgrade and specify the release you are upgrading to.
freebsd-update -r 10.1-RELEASE upgrade download and configure the new version
freebsd-update install start the install of the new version
shutdown -r now reboot your system to load the new kernel
freebsd-update install Finish the installs
There may be some questions that you are asked but for the most part you can accept the defaults
more information can be found in the freebsd-handbook