Ago is usually preceded by an expression of time.

The train went out ten minutes ago. (= It is ten minutes since the train went out.)
He died two years ago.
She phoned a few minutes ago.
It happened a long time ago.

Back and again have similar meanings, but there are some differences.

Back with a verb

Combine each pair of sentences into one simple sentence by using nouns or phrases in apposition.

1. That is my father. His name is James.

Combine each pair of sentences into one simple sentence by using participles.

1. He hurt his leg. He stopped walking.

2. He was unwilling to make another attempt. He decided to quit.

Person

The label person refers to the grammatical category which distinguishes participants in a conversation. English distinguishes three persons: first person, second person and third person.

Take care of

Take care of normally means ‘look after’.