I am using ubuntu 14.04 LTS.
I installed nodejs as mentioned here, and then I installed express by running
sudo npm install -g express@3
Installation of node in ubuntu is fairly a straight forward process. I don't know what gone wrong with your earlier attempt.anyway you can install it again if you wish. there are two ways to install node.
I always prefer the NVM method because it not only allows you to switch between versions but also avoids some of issues that otherwise you may face later. example, can't install npm packages globally without sudo.
Before you start remove your old installation
sudo rm -r ~/.npm
Now install nvm
curl https://raw.githubusercontent.com/creationix/nvm/v0.16.1/install.sh | bash
To activate nvm
Then install node
nvm install 0.10 nvm use 0.10
To set a default Node version to be used in any new shell
nvm alias default 0.10
Check everything done properly
Then install express
npm install -g express