To write for the web you must repeat the key words used in a Google search (called search engine optimisation – SEO) and use links to sites that use similar keywords in related content.
To write for the web you must write half as much as for print, bullet point lists and write the most important things first. This is called the inverted pyramid. Get rid of the generic first par of print news and pack the first line with proper nouns and key words.
To write for the web you must get your message across in the few paragraphs the reader can see without scrolling. That is usually only three or four paragraphs.
And good web writing involves breaking up the text into chunks. Each must stand alone and make sense to a reader landing there from a search engine, such as Google.
Is that it?
There is more to writing for the web, or good web writing, than that.
There are more tools you can use to help get it right and more analysis you can do to help improve your web writing.
But write like that and you will have made a good start.