～て

The て-form joins actions in the order they happen: "A and then B". Every verb but the last goes into the て-form, and the last one carries the tense and the politeness for the whole sentence.

Any number of て-forms can be chained, in the order the actions happen.

Tense goes on the last verb

The て-form has no tense of its own. The same て-clause works in a sentence about yesterday, today or tomorrow, and in plain or polite speech; only the final verb changes.

Putting each verb in the past and running them together does not join them.

• × 友達に会いました、映画を見ました → 友達に会って、映画を見ました

て or てから

てから stresses that the first action is over before the second starts: "after". The plain て-form just puts them in order.