go to there site, click on "Get web Hosting" up the top, than select your payment term (3 months to 36 months i think they do) to get there cheapest advertised prises you have to sign up for the longer terms. than add to cart and follow the given instructions. How ever I Think you should Look around at other alternative hosting company's That do not Promote unlimited bandwidth and disk space. If you still can not figure it out try getting on the there support they should be able to help you with that.
The best thing to do would be to find a different host! But if you log in and launch the Godaddy hosting control panel, it has all the tasks there for you.
OP, I think if you haven't already purchased a hosting, you should search the buy and sell things forum for getting a cheap hosting plan from someone, and they could help you set it up as well. Or I can provide you with hosting and I will transfer your domain and take care of everything else.
If you already bought a hosting plan, the support department should help you anyway. Just provide them with your cpmove or tar.gz backup and they will restore your files and databases to the new server. In case they don't help to transfer the data, you can do this yourself via FTP or the File manager which should be provided in the control panel.