FreeBsd makes keeping your system up-to-date relatively easy using a utility called freebsd-update.

simply run

freebsd-update fetch

to download all updates

then run

freebsd-update install

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

https://www.freebsd.org/doc/en/books/handbook/updating-upgrading-freebsdupdate.html