You can create an account in the ways described on the page that you posted from - you will need to use a different email account for it. But any content that you bought/downloaded with your existing account will remain tied to that account, so only that account wil be able to authorise its content, re-download them and download updates to its apps - generally it's better to have just the one account
I also have the original posters problem.
The response so far while its nice to get help, was not helpful. So many pronouns... for example, create new account on same page you posted from. I found this page via google, and logged in here... no point did i create an account to post this response. I did create an account etc, but still, "how you did this one" is not very helpful. The *REAL* question is not so much how to make an account, but how *should i*? There are legal and financial ramificaitons of same appleid or different id, how many devices can apps, tunes, books, movies be shared on - and what is considered a device by apple sharing policies? i think iphones and ipads are not, its just the mac's that are devices because it has the 'master' itunes running (as opposed to the 'mini' itunes player on the ipad and iphone)
Not sure if this is right or wrong, but so far i cant do anything because all the "FREE" apps need my credit card. Umm... free? So, what credit card with what account? same? different? share anything if different accounts? Questions, which should sound like follow-ons to the original question, how should i set my second account up?
I should add, its a second account on second system. shoudl i use same account on second system? there are two of us... kinda typical like a family setup - two parents. Is there guidance on how to operate two whole macs in one house - specifically about ID's, sharing, credit cards, etc.
The original poster asked the question by posting from this page : http://support.apple.com/kb/HT2731 - there is a link to that page just above his/her post (and why the title of their post starts 'HT2731'), which describes how to create an account, so that is why I replied to their post in that way.
An iTunes account can be authorised on 5 computer's iTunes at a time, and home sharing is therefore also limited to 5 computers at a time.
You should be able to create an account without needing to give a credit card : http://support.apple.com/kb/HT2534 e.g. select a free app in the store and click on 'create Apple id' when 'buying' it. I tried it a couple of weeks ago to check if it worked and that process worked for me, I was able to create an account and download a free app without giving a credit card number.
As I said on my original post it's generally best to have just the one account. All content that you buy/download via an account will be tied to that account, so only that account will be able to authorise its content on a computer, re-download it, or download updates to its apps. With automatic downloads or re-downloading an account's past purchases you can potentially tie a computer or device to that account for 90 days (I'm not entirely sure how that 90 days starts, some people have said that it has started for them, for others it hasn't) : http://support.apple.com/kb/HT4627