1. Explain it simply
已经 goes before the verb and 了 closes the sentence: Subject 已经 + verb phrase + 了.
他已经回家了 means 'He has already gone home'.
已经 and 了 work as a pair.
2. Show examples
他已经回家了。
Tā yǐjīng huí jiā le.
He has already gone home.
已经 + verb + 了
我已经吃饭了。
Wǒ yǐjīng chī fàn le.
I have already eaten.
已经 before the verb
我们已经学了两年了。
Wǒmen yǐjīng xué le liǎng nián le.
We have already studied for two years.
已经 with a duration
3. Share a tip
已经 pairs with 了 at the end, and 已经 goes before the verb - never after it.