I suggest the OP reads online guides
which would be found by searching the following...
(If I had to do it over again, I'd use a 100-page
notebook with one topic per page, to list links, CLI
examples, etc, as the HTM I save from sites I usually
never get around to re-reading...)
... cvsup ports tree
... upgrade selected ports
... make commmands (make build, make install, make deinstall
... blogs or guides mentioning portmanager, portmaster...
or even the pdf book (or two) that is avail.
Since they would explain a lot more than we could in less time.
(Unless a post or two in the HOWTO section already covers it)