I'll go ahead and assume your OS is XP but we need to know a bit more such as what browser you are using and if you actually tried going to the URL you provided us with - http://roybi.com.au/calendar

I think it is possible you meant http://ryobi.com.au/calendar as sure enough there is a link to some August entry page but going to that page does not show me anything like "yellow data entry boxes but they are not all yellow some are black". What I find in both Firefox and Internet Explorer on the August entry page is a form with a black background with textboxes, a dropdown box and a checkbox along with an enter button. On the link you offered (with typo corrected) there is no frorm of any sort.

On the page you linked to there are clickable "areas" labeled with the Month and Winners and Month and Closed and August and Enter Here and the Month is in YELLOW on all of them. Then I see Month and Coming Soon in gray that is not clickable so nothing happens. NO FORMS with any yellow text entry boxes.