Write the subject of the sentence and follow it with a vertical line. Write the verb after the vertical line. For example, a simple sentence 'It rained' would be written 'It' followed by a vertical line and then 'rained.' Underline the entire sentence.
Write longer sentences with two lines. If there is a second subject in the sentence, place it underneath the first sentence, under the horizontal line. For example, if a sentence read 'John sent Erik a letter' you would place 'John' on the top line followed by a vertical line, 'sent' on the top line, 'letter' on the top line after another vertical line, 'Erik' underneath the horizontal line under the word 'sent' and 'a' underneath the word 'letter' after a horizontal line.
Place any modifiers, such as adjectives, under the horizontal line. They should be placed under the word they are modifying, on top of a diagonal line pointing downwards to the right.
Put adverbs beneath the verb to show their function, even if the sentence diagram does not flow in a linear fashion. Sentence diagrams show relationships rather than exact sentences.
Place any expletives, such as the word 'there' floating above the diagram, attached by a few vertical dots. This means that the word is not really a part of the structure of the sentence.