i face this error while installing NS3 on ubunto i am new on linux kindly help me i suffered alot

when install gcc then this error show kindly help me
haider@ubuntu:~$ apt-get install gcc g++ python
E: Could not open lock file /var/lib/dpkg/lock - open (13: Permission denied)
E: Unable to lock the administration directory (/var/lib/dpkg/), are you root?

S Muhammad Haider Rizvi; Hello -

Please allow me to make these observations and point you in the right direction.

1) release 12.04 is End_of_Life and has no unpaid support.
<ubottu> Ubuntu 12.04 LTS (Precise Pangolin) was the sixteenth release of Ubuntu. !End-of-life was April 28th 2017. See https://lists.ubuntu.com/archives/ubuntu-security-announce/2017-April/003833.html for more information

2) the advisory " ... - open (13: Permission denied)" :
To make a change to the operating system one must have administrative authority . This authority is grantable to the 1st created user account by the 'sudo' protocol.
sudo apt-get update
sudo apt -get upgrade
sudo apt-get install <package(s)>
Be aware that apt-get is superseded in later releases by the tool ' apt ' .
sudo apt update

3) the advisory : ........ , are you root?

same as above and also that only one application of the package manager may be active at any given time.

Strongly advised that you install release 16.04 .

-Hope this helps-

thanks sir for guide me my queries

1- i have separate workstation for ubunto on separate laptop how i update this OS ?

2 i want to run Network simulator on ubunto so is it better i use VMplayer on windows and install latest ubunto ?

3- Now what yo suggest i quit here and go to 16.04?
another error appears when update any packet

 ubuntu-desktop
Processing was halted because there were too many errors.
E: Sub-process /usr/bin/dpkg returned an error code (1)

 S Muhammad Haider Rizvi;

You are asking some real tough questions that have no single answer.

1) Update current system:
make sure that the 12.04 is fully updated - IF the software repository is still in existence . I do not know the state of the precise repository.
what shows/results in terminal command
sudo apt-get update
sudo apt-get dist-upgrade

2) Network simulator:
I have no experience with this application and can not comment on a best practice.

3) /usr/bin/dpkg returned an error code:
IF the system is not updated OR the software repository has been turned away - you will experience errors that you have no path to recovery . Then the best course here is a clean fresh install of 16.04 .

Now if this is a production machine that you indeed insist on remaining on 12.04; there is:
ESM Canonical offers paid extended security support for 12.04 through the Ubuntu Advantage program. For more information, see https://ubuntu.com/esm . ESM is not an Ubuntu community offering; please direct questions about it to Canonical directly.

-looking for that best thing to do in a bad bad situation-