I work a lot on ACX, it is my preferred avenue to work with Indie Authors! There are other channels (Findaway, Spoken Realms) so look into them all to decide what is right for you.
“ACX is a marketplace where authors, literary agents, publishers, and other Rights Holders can connect with narrators, engineers, recording studios, and other Producers capable of producing a finished audiobook.” - www.acx.com
You upload your Ebook, state your budget and narrator/time requirements and the auditions start coming in.
The ACX website has so much information and makes it really easy to figure out. But, if you have issues please let me know and I am happy to help guide you!
Learn more here- https://www.acx.com/help/about-acx/200484860