trial-version
Testing the apps first...
.jar files
JAVA is 'ready for action' on your system (but deb packages won't work for you). Just download the Java Archives (JAR) and start from there.
java -jar SMonitor.jar -v
java -jar ttimer.jar -v
.deb packages
Installation via command line
sudo dpkg -i [/home/"NAME"/Downloads/]ttimer-2.0.deb
sudo dpkg -i [/home/"NAME"/Downloads/]smonitor-2.0.deb
There are some graphical tools to install Debian packages (.deb) too, e.g. "qapt", "gdebi", ...
To remove the packages afterwards is also very easy
sudo dpkg -r [/home/"NAME"/Downloads/]ttimer-2.0.deb
sudo dpkg -r [/home/"NAME"/Downloads/]smonitor-2.0.deb
Of course, you could leave them on your system as well.
;)