I downloaded and installed JForum 2.1.9, and it's working, but I don't know how to add a new Forum, I cannot find a screen for that also when I added manually in DB, I cannot find it, even after restart the server
Welcome to JavaRanch. Forums can be added via "Admin Control Panel", a link to which is at the bottom of each page if you're logged in with an admin account. I've never tried to add forums via direct DB manipulation, but I would imagine that the information goes into more than one table; so it's not quite as easy as it may look at first.
You may want to consider this newer branch of JForum, which has lots of improvements over the defunct 2.1.9 version. (In the interest of full disclosure, I'm a committer on that branch.)
Goto the appropriate subfolder of /config/database for your database. There you will find scripts which pre-populate (and can tear down) JForum databases e.g. for MySql try,
the mysql_db_struct.sql script builds tables, we're not interested in that. But the mysql_db_data_dup.sql script populates tables, so we are interested (!). Here's the script used to create the demo category/forum,
Should be roughly the same form for the original JForum code.
If you tried something similar, then the problem is not there.. This script code suggests that, so long as there is an initial setup defining roles and the like, it's that simple - but I would still heed the warning in the post above.