Every sentence contains two main parts: subject and predicate.
Every sentence will contain at least two words: a NOUN (or a PRONOUN) and a VERB.
The SUBJECT is what the sentence is about. The PREDICATE is what is said about the subject.
If the sentence is a command, it may contain only one word. For example, Hurry! is a sentence. Hurry is a verb. The sentence is a command. The sentence is about the person being told to hurry. The subject is understood to be You.
To write good sentences, you also need to learn these additional terms:
The best way to teach (and to learn) the parts of the sentence is to take your time and get in plenty of practice with exercises.