What to write?
The main thing to focus on is what you say: you need to be very brief and clear, you have about 15 seconds to get your point across before people will leave the page. If your page is about an event, organisation or service then the date, time and location should be the first things a visitor sees – at the top of the page. You can put more information below that, but try and keep it to one or two sentences.
If your page needs to contain longer/more complex information (and few do) you have those 15 seconds to catch your readers attention so they will stay: use a summary, a question or an interesting fact to appeal to their curiosity so they will read on.
There is an example of what a well organised page looks like below: you can see some simple, clear information at the top in bold text, with further information below in normal text, then below that there are some short paragraphs with headings.