Here is how to install node and npm in ubuntu.
The ~/local directory is to store all of your user-level packages, btw.
mkdir -p ~/local
mkdir -p ~/node-latest-install
cd ~/node-latest-install
curl http://nodejs.org/dist/node-latest.tar.gz | tar xz --strip-components=1
./configure --prefix=~/local # if SSL support is not required, use --without-ssl
make install
cd ..
rm -rf ~/node-latest-install
Then in your ~/.bashrc file, append the following line.
export PATH=$PATH:'~/local/bin/'
Then source your new .bashrc by source ~/.bashrc
If everything goes well, the following commands should return the version info.
node -v
npm -v