Installing software in Ubuntu from the repositories is very very easy, first you start by going into System >Administration >Synaptics Package Manager.

After cliking on Synaptics Package Manager you will see the application comeup.

Then select search at the very top of the application screen and enter the application name if it is available for Ubuntu it will showup on your results list.

Once you see the application in the results list simply right-click it and you will see a list of options, simply select Mark for Installation.

Then go to the very top and click Apply you will see a confirmation window popup click Apply again.

After the last step you are pretty much done, the manager takes over and downloads the required files. Click Close

You are done!