I know that in a sentence of three or more words or phrases we need commas, but are the sujects supposed to be capitalized if not why or why not. Sample sentence below:

As I have a Web design and interactive media associate degree, I do have experience in basic Web design screen and graphic design, basic Web scripting, as well as Web systems management and structure.

Where did those rules come from? Who made them up??!!

She ate salad.
That's a 3-word sentence that needs no commas.

She ate salad and soup for lunch.
That's a 7-word sentence that needs no commas.

Common nouns and pronouns are not capitalized; proper nouns are capitalized.

LOL!

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Here are the rules for commas and capitalization in English:
Commas = http://grammar.ccc.commnet.edu/grammar/commas.htm

Capitalization = http://grammar.ccc.commnet.edu/grammar/capitals.htm

In a sentence with a list of three or more words or phrases, it is generally recommended to use commas to separate the items in the list. However, the capitalization of the subjects in the sentence is a separate issue.

In the sample sentence you provided, the subjects are "Web design and interactive media associate degree," "basic Web design screen and graphic design," "basic Web scripting," and "Web systems management and structure."

Whether or not these subjects should be capitalized depends on the specific context and style guidelines you are following. In general, proper nouns and the first word in a sentence are capitalized, while other words are typically written in lowercase (unless they are titles or emphasized words). However, for titles or proper nouns that are composed of multiple words, different style guides may have different rules.

If "Web design and interactive media associate degree" is a specific degree program or title, it is common to capitalize each word in the title. Similarly, if "basic Web design screen and graphic design," "basic Web scripting," and "Web systems management and structure" are specific course titles or areas of study, they may also be capitalized. However, if these phrases are not specific titles or proper nouns, they can be written in lowercase.

To determine whether or not to capitalize the subjects, you should consider the specific context, style guidelines, and any specific titles or names that may be involved.