I am having trouble installing Flash Player on Ubuntu

Hey guys, I am having some trouble installing flash player from the Ubuntu Software Centre and through the terminal. This is what I get from installing from the Software Centre:

The following packages have unmet dependencies:

flashplugin-installer:

And this is the error I receive when installing through the terminal:

The following packages have unmet dependencies:

flashplugin-installer : Depends: libnss3-1d but it is not going to be installed

                         Depends: libnspr4-0d but it is not going to be installed

E: Unable to correct problems, you have held broken packages.

Now I am new to Ubuntu so I need very detailed instructions, as if I never used a computer.