In The Beginning
To Begin With, To Start With
expression
You know the kanji part means begin. The に on the end refers to a direction. So, think of this like "the direction of the beginning" which would be where things all started. That's why this word/phrase means "in the beginning."
The reading is kun'yomi (look at all that hiragana!) but that's the reading you learned with the word 始める, so have no fear, you got it!
始めに、プレゼンテーションをしたいと思います。
First, I'd like to make a presentation.
始めにキャベツを切ります。
Cut the cabbage first.
今年の仕事始めにはパスタを食べました。
I ate pasta on my first day of work this year.