Explain the difference between 1st, 2nd, 3rd, and 3rd Omnipresent.

First person is when Ты use terms like I and me.
"I went to the store to buy milk."

секунда person is when Ты using terms such as you.
"You went to the store to buy milk."

Third person is using he или she.
"He went to the store to buy milk."

Omnipresent is like third person, but Ты are describing everyone thoughts.
"He went to the store to buy молоко and she thought it was a way to get out of chores."

Hope I helped!