When do we use 'has' and 'had' together in the same sentence? can you give me examples with explanation?

1 . I have had lunch .

2. He has had lunch .

3. I had had lunch before you came.

Explanation:

This is one of the most confused about combinations as per my experience .I would firstly tell a bit of grammar part and then clarify with real day to day usage .

THE CONFUSION IF AT ALL COMES IS BECAUSE OF TWO DIFFERENT USAGES OF WORD “HAVE” . THEY LOOK AND SOUND LIKE SAME BUT PLEASE TREAT THEM DIFFERENTLY . So let's separate them like one of them is same like “ “AM,ARE,WILL,SHALL, “ the helping or auxiliary verbs ,and the second. “have “ is just like “ drive, eat, drink, watch” the main verb “ or I prefer to call “ Action”.

1. read the following excerpt from franklin d. roosevelt's "fireside chat 19":

on the other side of the picture, we must learn also to know that guerilla warfare against the germans in, let us say serbia or norway, us; that a successful russian offensive against the germans us; and that british successes on land or sea in any part of the world strengthen our hands.

remember always that germany and italy, regardless of any formal declaration of war, consider themselves at war with the united states at this moment just as much as they consider themselves at war with britain or russia. and germany puts all the other republics of the americas into the same category of enemies. the people of our sister republics of this hemisphere can be honored by that fact.  

the true goal we seek is far above and beyond the ugly field of battle. when we resort to force, as now we must, we are determined that this force shall be directed toward ultimate good as well as against immediate evil. we americans are not destroyers — we are builders.

analyze the effectiveness of this excerpt. how does it function within the speech as a whole? how does the structure of the excerpt to convey the speech's purpose and key points? support your argument with evidence from the speech. (10 points)