Ik heb het tegen Anna gezegd.

This is the perfect tense.

• heb = the finite auxiliary verb
• gezegd = the past participle of zeggen

In a normal Dutch main clause, the finite verb goes in second position, and the past participle usually goes toward the end:

• Ik heb het tegen Anna gezegd.

Dutch often uses the perfect tense for completed past actions in everyday speech, where English might simply use the simple past.

Because zeggen forms its perfect tense with hebben.

Many Dutch verbs use hebben in the perfect.
Only certain kinds of verbs commonly use zijn, especially verbs of movement or change of state, such as:

• Ik ben gegaan
• Hij is gevallen

But with zeggen, you say:

• ik heb gezegd
• not ik ben gezegd

Het is the direct object pronoun, meaning it.

It refers to the thing that was said, usually something already known from the context.

So the structure is:

• Ik = subject
• heb gezegd = have said
• het = it
• tegen Anna = to Anna

If you say exactly what was said in a dat-clause, Dutch often leaves out het:

• Ik heb tegen Anna gezegd dat ik later kom.

So het is common when the content is not repeated and is just understood as it.

With verbs of speaking, Dutch very often uses tegen for the person you speak to:

• iets tegen iemand zeggen

So:

• Ik heb het tegen Anna gezegd

is a very normal pattern.

You may also hear:

• Ik heb het aan Anna gezegd
• Ik heb het Anna gezegd

These are possible too, but tegen iemand zeggen is extremely common and natural in everyday Dutch.

A rough guide:

• tegen = very common with spoken communication
• aan = also possible, sometimes a bit more like to
• no preposition = also possible, especially with pronouns like haar

Yes, you can.

In that version, Anna is the indirect object without a preposition:

• Ik heb het Anna gezegd.

This is also grammatical Dutch. With pronouns, this is especially common:

• Ik heb het haar gezegd.

Using tegen Anna makes the to Anna relationship more explicit. Both versions are possible, and which one sounds most natural can depend on style, rhythm, and speaker preference.

Because short, unstressed pronouns like het usually come early in the middle part of the sentence.

Dutch word order tends to place:

1. short pronouns first
2. then longer phrases like prepositional phrases

So this is natural:

• Ik heb het tegen Anna gezegd.

This sounds much less natural:

• Ik heb tegen Anna het gezegd.

That second version would only work in a very marked, contrastive situation, where het gets special emphasis.

Yes. Dutch allows that for emphasis or topic marking.

For example:

• Tegen Anna heb ik het gezegd.

This puts extra focus on Anna—as if you are contrasting her with someone else.

When you move something to the front in Dutch, the finite verb still stays in second position:

• Tegen Anna
  • heb
    • ik
      • ...

So the word order changes, but the sentence remains fully grammatical.

Both can often be translated similarly, but the tense is different.

• Ik heb het tegen Anna gezegd = perfect tense
• Ik zei het tegen Anna = simple past

In modern spoken Dutch, the perfect tense is often more common for completed actions in conversation.

The simple past is also common, but often sounds more like:

• a narrative style
• written storytelling
• or just another way of describing a past event

So in everyday speech, Ik heb het tegen Anna gezegd is extremely normal.

Usually:

• Ik heb het niet tegen Anna gezegd.

This is the most natural neutral negation.

The exact meaning can depend on what you are stressing, but very often it means something like:

• I didn’t say it to Anna
• It wasn’t Anna that I said it to

Dutch negation placement can shift for emphasis, but for a sentence like this, niet normally comes after the pronoun and before the prepositional phrase.

You invert the subject and the finite verb:

• Heb je het tegen Anna gezegd?
• Heb ik het tegen Anna gezegd?
• Hebben jullie het tegen Anna gezegd?

So the finite verb comes first in a yes/no question.

That is a very common Dutch pattern:

• statement: Ik heb het tegen Anna gezegd.
• question: Heb ik het tegen Anna gezegd?