We need to install java to successfully install Openproj.
To install java follow the link below.
Then install Openproj as shown on this video.
After this, you have to do some changes with java i.e
$HOME/.openproj/run.conf and Change
JAVA_OPTS="-Djava.vendor=Sun -Xms128m -Xmx768m"
You are done with it.