There doesn't appear to be a mainstream UI for BSD ports.
(Curiously, the Mac OS X equivalent, MacPorts, has at least two current UI projects.)
To search you use ls, cd, and find. To install you "cd <dir> && make install".
If you are installing freebsd you should already be comfortable enough to not need a pretty gui hiding these very simple details.
make search name=name_of_port
to search for a port by name and:
make search key=key_to_search_for
to search by key. You can also use quicksearch instead of search to reduce the verbosity of the results. If you read the ports man page, you will find a bunch of other nifty things you can do with the ports system.