This page is all about plumbing. And has a lot of white space. So, do you need to be able to speak HTML to write these? (I see there's no line breaks on screen)
No you don't need to know about HTML, but; formatting a wiki page does require some learning of the wikis own version of a markup language, which is then transformed into HTML by the wiki software.
To start a new paragraph, leave a blank line.
The are a set of buttons at the top of the edit page. They create example content, eg for Bold text , Italic text, etc use those, or just remember on media wiki three quotes is bold, two quotes italic.
for a link enclose URL in square brackets: bathroom tiles
Well, now we are back on the topic of plumbing let's try some organisation:
water is wet, very wet... a link to a page about [water] ?
is best for bathing
is best for drinking