1. Double click on the package.deb file and install it by selecting Install Package option
2. or by using command line from ubuntu terminal:
sudo dpkg -i package.debdpkg is a debian package manager that manages debian packages. There are many options that can be used and in this case -i option is for installation.
3. To uninstall the package is pretty simple as well. It can be done via Synaptic Package Manager: search by the package name and then uncheck it for removal selection.
4. or via terminal by invoking a command with -r option:
sudo dpkg -r package.debThat's so easy isn't it? so good luck dudes!