Wherefore  - The Greek word translated as "wherefore" either emphasizes the truth of something ("certainly," "really") or it simply continues an existing narrative.

if  - The Greek word translated as "if " means "if might" indicates more of an expectation of something happening than "if" alone.

they -- This is from the third-person, plural form of the verb.

shall -- (CW) This helping verb "shall" does not indicate the future tense, but that the verb describes a possibility, the subjunctive voice. A "might" or "should" in English is more appropriate, but is assumed in an "if/when/whoever/except" clause. Helping verbs are not needed in Greek since the main verb carries this information in its form.

say " - "Say" is from means "to say" and "to speak" also. However, it has less a sense of teaching and more a sense of addressing and proclaiming. It is not in the future tense, but a form indicating something that might happen in the past, present, or future.

unto -- This word "unto" comes from the dative case of the following word that requires the addition of a preposition in English. The most common is a "to" for the English indirect object.

you, -- The Greek pronoun "you" here is plural and in the form of an indirect object, "to you," "for you," etc. 

Behold,  - "Behold" is from an adverb meaning "Lo! Behold!" and "See there!" In a humorous vein, this about how Jesus uses this like we use the phrase "ta-da" in a magic show, or "voila!" in French. Since Christ just used this term to describe his own predictions, the humor seems more pronounced.

he -- This is from the third-person, singular form of the verb.

is  - The verb here, "he is," is the common form of "to be" in Greek. It means to have a certain characteristic or remain in a certain condition. The form could be "he is" but it could also be "it is." The reference here, however, seems to clearly be the "Christ" used in Matthew 24:23.

in  -   -- The word translated as "in" means "in," "within," "with," "during" (time),  or "among"  with a dative object as the one here. 

the  - -- The word translated as "the" is the Greek definite article, without a noun, it has the sense of "the one." The Greek article is much closer to our demonstrative pronouns ("this," "that," "these," "those") than the English "the." See this article for more. 

desert;  - The "desert" here means the complete lack of everything, including friends. It is translated both as "desert" and "wilderness." However, the word means emptiness, even in the sense of "loneliness." Another form of this word was translated as "desolation" in Matthew 24:15.

go  - (WF) The word translated as "go forth" means literally "to go or come out," but it has a secondary meaning of "making something come true." This is not a command, but a subjunctive, requiring a "should" or a "might."

not  - The negative "not" used here is the Greek negative of a subjective opinion, commands, and requests. The sense is that "you don't want" to do something, not that it isn't done or don't think something that might be true. If it wasn't done or wasn't true, the objective negative of fact would be used. This goes with the subjective form of the verb.

forth:  - -- This is from the prefix of the previous verb that means "out of."

behold  - "Behold" is from an adverb meaning "Lo! Behold!" and "See there!" In a humorous vein, this about how Jesus uses this like we use the phrase "ta-da" in a magic show, or "see!" in French. Since Christ just used this term to describe his own predictions, the humor seems more pronounced.

he is -- (IW) There is nothing that can be translated as "he is" in the Greek source.

in  -   -- The word translated as "in" means "in," "within," "with," "during" (time),  or "among"  with a dative object as the one here. 

the  - -- The word translated as "the" is the Greek definite article, without a noun, it has the sense of "the one." The Greek article is much closer to our demonstrative pronouns ("this," "that," "these," "those") than the English "the." See this article for more. 

secret chambers;  - (CW) The word translated as "secret chamber" means a "treasury" or a "storeroom." The idea is a room without windows and just one door. This word is translated elsewhere as "closet."

believe  - (WF) The Greek word translated as "believe" does not apply to religious belief as much as it does trust in other people, especially their word. Christ usually uses it in contexts, as the one here, that apply to trusting words. The negation of "belief" with the objective, instead of subjective, negative, equates trust with a fact. This is not a command, but a subjunctive, requiring a "should" or a "might."

it -- There is no Greek pronoun here, but Greek does not need pronouns when the object can be assumed from the context. In English, they are added for the subject-verb-object form of our sentences.

not.  - The negative "not" used here is the Greek negative of a subjective opinion, commands, and requests. The sense is that "you don't want" to do something, not that it isn't done or don't think something that might be true. If it wasn't done or wasn't true, the objective negative of fact would be used. This goes with the subjective form of the verb.