If you upgrade, follow the instructions in the file ChangeLog.
New installations: as root untar this archive in the /tmp directory. Then cd /tmp/mbsebbs-0.92.0 and type sh ./SETUP.sh. On FreeBSD and NetBSD you must force the bash shell, so type bash ./SETUP.sh. For further instructions see the file /tmp/mbsebbs-0.92.00/INSTALL.