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Here is the solution to your password issue. When it asks for your password, you need to type the password to your user account. (The password you use to login or unlock your computer) It will *not* display any characters, but the password is still being entered. That is one of the security features, as annoying as it may be. When you type the password in, then you simply hit enter, and you should be good to go.
As far as the "Unable to lock the administration directory (/var/lib/dpkg/), is another process using it?" error, that means something else is using the apt program. If the synaptic package manager is open, then you need to close it. Your computer could be installing updates, or you have the update manager open. This will cause the error stated, because each of these programs have to 'lock' the admin directory to ensure that only one program is making changes to the system at one time.
There was a thread about this error on askubuntu.com that might point you in the right direction: http://askubuntu.com/questions/163030/cannot-open-lock-file-var-lib-dpkg...
N.B. The reader updated their original question to state that they had resolved the first issue, and were now getting the following prompt: OK, I figured out the password thing, now its just not working. It keeps saying "Unable to lock the administration directory (/var/lib/dpkg/), is another process using it?" and "cannot execute h"