Bitte schauen Sie zuerst ins Inhaltsverzeichnis; dort steht jedes Stichwort mit der richtigen Seitenzahl.

Because this is a polite instruction/request, so German uses the formal imperative.

• Sie schauen = you look / you are looking in a normal statement.
• Schauen Sie = look in a polite/formal way.

This is the standard pattern for the formal imperative:

• Kommen Sie bitte. = Please come.
• Lesen Sie den Text. = Please read the text.

So Bitte schauen Sie zuerst ... means Please look first ...

Bitte makes the sentence polite, like please in English.

It can appear in different places:

• Bitte schauen Sie zuerst ...
• Schauen Sie bitte zuerst ...

Both are natural. In this sentence, putting Bitte first gives the whole sentence a polite opening.

Ins is the contraction of in das.

• in das → ins
• in dem → im

Here, ins Inhaltsverzeichnis is used with the idea of looking into the table of contents.

So:

• ins Inhaltsverzeichnis schauen = to look into the table of contents

By contrast:

• im Inhaltsverzeichnis = in the table of contents, as a location

You can see both ideas in the full sentence:

• Schauen Sie ... ins Inhaltsverzeichnis → look into it
• dort steht ... → there it says / there you find ...

The word is das Inhaltsverzeichnis, so it is neuter. That is why you get:

• ins Inhaltsverzeichnis = in das Inhaltsverzeichnis

Unfortunately, grammatical gender in German often just has to be learned with each noun. A good habit is to memorize nouns with their article:

• das Inhaltsverzeichnis
• das Stichwort
• die Seitenzahl

Zuerst means first or first of all.

It is an adverb, and German adverbs are fairly flexible in position, but they often appear in the middle field of the sentence, like here:

• Bitte schauen Sie zuerst ins Inhaltsverzeichnis.

This sounds very natural. It tells the reader what to do before anything else.

Comparable examples:

• Lesen Sie zuerst die Frage.
• Denken Sie zuerst nach.

Dort means there and refers back to the table of contents.

So:

• dort steht ... = there it says ... / there you will find ...

Yes, da is also possible in many contexts:

• Da steht jedes Stichwort ...

But dort can sound a little more explicit or slightly more formal/written. In a sentence like this, dort fits very well.

German often uses stehen for written information that appears on a page.

So:

• Dort steht ... literally = There stands ...
• natural English = It says ... / You find ... there

This is very common:

• Was steht im Text? = What does the text say?
• Das steht auf Seite 10. = That is written on page 10.

So steht does not mean something is physically standing up in this context. It means the information is written there.

Jedes Stichwort means each keyword / every entry. It is singular and distributive: it treats the entries one by one.

• jedes Stichwort = each keyword
• alle Stichwörter = all keywords

Both can make sense, but they are slightly different in focus:

• jedes Stichwort emphasizes that every single entry has a page number
• alle Stichwörter refers to the whole set more collectively

Also, Stichwort is neuter:

• das Stichwort
• jedes Stichwort

Because Stichwort is:

• neuter
• singular
• nominative (it is the subject of steht)

The basic pattern is:

• masculine: jeder
• feminine: jede
• neuter: jedes

So:

• jeder Mann
• jede Seite
• jedes Stichwort

In this sentence, jedes Stichwort is the thing that steht there.

It is in the dative case because the preposition mit always takes dative.

So:

• mit der richtigen Seitenzahl

Breakdown:

• mit → always dative
• die Seitenzahl → feminine noun
• feminine singular dative with definite article → der
• adjective after der in dative singular → richtigen

So the phrase means:

• with the correct page number

Because the adjective comes after der in a dative feminine phrase:

• mit der richtigen Seitenzahl

After a definite article like der, the adjective usually takes a weaker ending. In this case, the ending is -en.

Compare:

• nominative: die richtige Seitenzahl
• dative after mit: mit der richtigen Seitenzahl

So the change is caused by the case and the article.

• die Seite = page
• die Seitenzahl = page number

So:

• auf Seite 12 = on page 12
• mit der richtigen Seitenzahl = with the correct page number

In a table of contents or index-style context, Seitenzahl is more precise, because it refers to the number that tells you where to find something.

Because they are nouns, and in German all nouns are capitalized.

So in this sentence:

• Inhaltsverzeichnis
• Stichwort
• Seitenzahl

are all capitalized because they are nouns.

This is one of the most noticeable spelling rules in German and is very helpful when reading, because it makes nouns easy to spot.