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Currently I have Firefox 45.02 and Thunderbird 38.6.0 installed on my PC. I have downloaded Firefox 55.0.3 and Thunderbird 52.3.0 from the respective websites but how do I run and install these applications. If I click on the downloads, all I get is a list of files but I do not see a setup-exe file anywhere. I am not familiar with Linuc commands but what do I need to run and install. I am running Ubuntu 16.04. All responses would be appreciated.