I set up a new business mail account in Google for you.
When you establish and determine something, you are making an establishment. When you make that into a verb, you have the word to establish. It also works for tech things, like to set up your computer settings.
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well. Careful because the 設 gets shortened to せっ.