If your install did work then to install Apache you will need to type something like
apt-get install apache2
Hopefully it goes without saying that if you are asking this the machine should not be exposed to the internet.
For Debian-based distributions, of which Ubuntu is one, you use apt-get or aptitude to install and remove packages as well as to upgrade existing packages. You can also use apt-cache to search for packages. I suggest you read up on these commands if you want to use Ubuntu in future as they are used regularly. (I have to confess that I always use apt-get and have not used aptitude so I don't know the differences between the two but suffice it to say that you should endeavour to use one or the other and not both)