When you create a page and decide what words to use, what pictures to include, which icons will hold place in your navigation scheme, you've entered a world of communication with a wide range of people.
Imagine all the potential visitors to your site, and think about how you can communicate with them as effectively as possible. Remember that there will be people of different sizes, shapes, races, cultures, genders, nationalities, economic situations, abilities, and educational levels.
You definitely have to make some decisions regarding who your target audience is going to be for your pages. Is it enough to design a page so that it looks the same, or very similar in both Firefox, and Internet Explorer? Should you take steps so that your site is accessible to people who have visual limiations?
And just what do colors mean to people from other cultures? Do they have significance from one culture to another? Do certain choices of words and phrases have different meanings based upon culture, or education level, or gender?
We spend a lot of time and effort learning about usability, and how to make a web page a good experience for visitors. We also expend energy on trying to build web pages based upon keywords and phrases that we hope people will use to find the information that we include on our pages. Yet how much effort do we spend on learning about our language and pictures and icons, and how people interpret them?
Ferdinand de Saussure had this to say on the study of signs:
It is... possible to conceive of a science which studies the role of signs as part of social life. It would form part of social psychology, and hence of general psychology. We shall call it semiology (from the Greek semeîon, 'sign'). It would investigate the nature of signs and the laws governing them. Since it does not yet exist, one cannot say for certain that it will exist. But it has a right to exist, a place ready for it in advance. Linguistics is only one branch of this general science. The laws which semiology will discover will be laws applicable in linguistics, and linguistics will thus be assigned to a clearly defined place in the field of human knowledge.
An excellent resource to learn more about semiotics can be found at Semiotics for Beginners
Some of that site becomes technical really quickly, and some of it delves more into history than it should to make it light reading. But the sections that look at modern advertisements and analyze them are priceless.
I especially enjoyed the page about Rhetorical Tropes, or the art of persuasion. These include metaphors, metonyms, synecdoche, and irony. If you can get a good grasp of what those mean, it might just change the way you write (and choose pictures and icons) significantly.
And a better understanding of how you are writing might just help you target better what you are writing for your chosen audience.