How to install Python 2.7, which has already been downloaded

You should generally avoid installing software on Ubuntu (or most GNU/Linux operating systems) by manually downloading files and installing them. It is preferable to install the package for the software, provided in the official software sources. For Ubuntu, and for installing Python, you should install the package called python-defaults. Depending on what release of Ubuntu you are using, that might give you python 2.7.2 or some other version. If it gives you another version, you might look for a specific python package for a version suitable for your needs. If you need help finding this or it appears that there is no such version available, please let us know and we can provide more detailed advice (please make sure to specify what Ubuntu release you are running and specifically what constraints you are operating under with respect to what Python version you must use).

To install a package graphically, you can use the Ubuntu Software Center. In the Software Center, you can search for the name of the package you want to install, or for part of the name, or for a word in its description. So to install python-defaults, search for that. If you want to see the different python and python-related packages that are available, just search for python.

To install a package from the command-line, open the Terminal (Ctrl+Alt+T) and run these commands:

sudo apt-get update
sudo apt-get install python-defaults