The Feast of Atonement provides us with a view into God's plan of salvation for mankind that is, as would be said today, action packed!
There were a great number of things the Israelite priest were required to perform during this Feast (Deuteronomy 16:1-30). As for the people, they were to afflict their souls (fast) as they observed this High Sabbath rest day (Deuteronomy 16:31). So you could ask, what does all of this have to do with me, for all of this is old covenant. Some will say I am under the new covenant and those things have nothing to do with me. Well here I would ask you to go to your Bible and read for yourself what the new covenant is and with whom it is made (Hebrews 8:7-10, Jeremiah 31:31-33). Well the next question should be, then just how do I as a none Israelite get into the new covenant? (Romans 11:11-18) Has God appointed a High Priest over His new covenant church? (Hebrews 2:14-18)
Now knowing what the Bible says in these passages, hopefully you will begin to see what this Feast points to in God's plan of salvation. there is recorded in the book of Acts an event (Acts 8:26-39). This person needed and wanted help in understanding God's word. I believe somewhere along the way he prayed and asked God for help and God answered. There should be no shame in not knowing, but rather to not seek and even greater to not receive. May God bless you and grant you understanding of His Feast of Atonement.