well, actually you do need it converted. it is currently phpbb 2
in order to update you will have to convert from 2 to 3.1
if you update none of your MODs will work, none of your styles will work etc. but all of your posts and members and forums/topics etc. will still be there just as they are now.
you will have to find a new style and see if any of your MODs have been ported over to extensions for the newer versions.
now, if you want to keep phpbb2 then I would suggest you visit http://phpbb2refugess.com
that is about the only place left that offers any kind of support for it.
the last version of phpbb 2 was 2.0.23 and it reached end of life around 10 years ago.