I've used bash shell in all my Linuxes and in Mac OS X. I understand that tcsh is the default shell in FreeBSD. If I were to install bash, how would I make it my default shell?
Changing one's login shell is covered by The FreeBSD Handbook, in the chapter called Shells. It also points to a chapter called Installing Applications: Packages and Ports that will tell you what you need to know for installing
bash from a FreeBSD package would automatically update
The steps involved, assuming an otherwise properly set up FreeBSD system, could probably be summarised into
sudo pkg install bash chsh -s /usr/local/bin/bash
There is also the pw utility.
pw usermod <user> -s /usr/local/bin/bash