Writing for the Web is not much same as writing for print. As the first demads a much more concise style than the later.

It is clear if  you ever tried to read your local newspaper online? How about The Hindu or The Wall Street Journal? It just isn't the same. Do you know why?  Because articles desplayed in the screen is not much easier to read as those published in print.

How the web is different?

1. Because  typical computer monitors have a resolution of 96 dpi. Compare that with a printout from a laser printer that has a resolution of 600 dpi, or a magazine page that can be upwards of 2400 dpi. And more over the text on computer screen places a strain on reader's eyes.
2. Words can be hyperlinked to other pages and URLs
   This is the greatest advantage of web pages. We can link words and images in to other web pages, photos, videos, sounds, blogs, chat forums etc.

How to write for the web.?

1. Write less cause 'less is more'
   Because of the strain placed on readers when reading on a computer screen, you can't expect them to read a 2,000 word article. Research has shown that most readers tend to scan an article before reading. Articles longer than 1,000 words will likely turn off your audience and result in few people reading your article.
2. Write brief paragraphs
   You should condense your writing to include only the most crucial points and eliminate everything else. Put only the  the necessary content and leave the rest out.
3. Utilize headings and lists
   As i have already said people tend to scan web articles as opposed to reading them from the first word to the last. So you should use heading to make them easy to find out what they are looking for. A great way to turn a print article into a readable web article is to transform it into a top 10 list. Lists make it easy for readers to scan and read only what they are interested in.
4. Use  hyperlinks 
   Hyper links are the primary advantage of a web writer. It hsould be used often. Linking allows you to provide the reader with a roadmap of information.  Common things to link include reference pages, news sources, audio and video, forums, and applications that will enhance the reading experience.

Now i conclude with the last but very importent point that never try to do all these by yourselves but seek a professional content writer.