Installing programs in Ubuntu can easily be accomplished by going to Applications>Add/Remove This is the more 'easy' approach- you can also use System>Administration>Synaptic Package Manager' if there is something specific you want to install.
As for your wireless, you don't actually need software from your ISP in order to use the connection. You should be able to click on the network connection logo at the top of your screen and set up your wireless access from there.
Also- before making future posts please search to see if someone has asked the question before. If not, and you need to make a new post, please make the thread title more descriptive- something along the lines of 'How do I add or remove programs in Ubuntu 8.10?'