If II たら
A while back we found もし as the word that means 'if'. たら is added to the end of verbs to give the meaning of 'if this is done, then this will happen'
It is formed by finding the simple past form and adding a ら
anata ga kitara kare wa kaeru
If you are coming, he will go home.
The simple past form of 来る is 来た.The 2nd phrase is conditional on the たら phrase.
gojira ni attara doushiyou.
What should I do if I meet Godzilla?
You can also use it with nouns by using the simple past form of desu: だった