Omni 1:1 - 1:5

Omni 1:1 Behold, it came to pass that I, Omni, being commanded by my father, Jarom, that I should write somewhat upon these plates, to preserve our genealogy—

Omni now takes up the responsibility of keeping the record which is also a means to keep a genealogy of his family as well.

Omni 1:2 Wherefore, in my days, I would that ye should know that I fought much with the sword to preserve my people, the Nephites, from falling into the hands of their enemies, the Lamanites. But behold, I of myself am a wicked man, and I have not kept the statutes and the commandments of the Lord as I ought to have done.

Omni relates that most of his life was spent in fighting Lamanites. But unlike his father Jarom, Omni confesses to be a wicked man who did not live up the commandments of the Lord or carried out the requirements of the law of Moses, as he should have.
[Interesting that Omni confesses his spiritual condition here. One would think that a brief statement of the history of the Nephites would be sufficient. And there would be no need to include some form of a confession as to his own condition. But maybe Omni as he was sitting down to write these few words was doing a little soul searching and wondering what could he write that might be a help to future readers. Wanting perhaps to included some kind of lesson to pass down like his predecessors, he chose to say that a bad example does not produce the peace and joy one normally wants in his life. His wickedness only brought misery, suffering and warfare.]

Omni 1:3 And it came to pass that two hundred and seventy and six years had passed away, and we had many seasons of peace; and we had many seasons of serious war and bloodshed. Yea, and in fine, two hundred and eighty and two years had passed away, and I had kept these plates according to the commandments of my fathers; and I conferred them upon my son Amaron. And I make an end.

He is writing 276 years after Lehi left Jerusalem or 38 years after Jarom recorded his few words. Omni reports that there have been time of grave warfare with the Lamanites, but there have been times of peace as well. In the 282nd year, Omni passed the plates on to his son Amaron.

Omni 1:4 And now I, Amaron, write the things whatsoever I write, which are few, in the book of my father.

Amaron will be brief in his remarks as was his father.

Omni 1:5 Behold, it came to pass that three hundred and twenty years had passed away, and the more wicked part of the Nephites were destroyed.

Amaron reports in the 320th year that the most wicked of the Nephites have been destroyed.