How would I do a web diagram on the following sentence for adjectives?
My eleven brothers received an abundant supply of food.
My, eleven modify brothers
an, abundant modify supply
So you have 4 words that are considered adjectives (although your teacher may or may not care about the article, "an").
I've never heard of a web diagram for adjectives, but you may find out how in one of these sites:
http://www.google.com/search?hl=en&q=web+diagram+sentence&aq=f&aqi=&aql=&oq=