What particular exam do I need to get? Would that be TOEFL®?

[Sanunai]

Hi there, Good morning, I'm here at the office right now, actually I want to ask my opinion because I'm working in Training Center of language here in the Philippines, I worked as a Language Trainer, and I want to pass the examination under with TOEFL, My line of work as of now, I'm Teaching American Accent (Standard American Accent)which I train students who wanted to work in a Call Center companies , but I have a some Problem in writing sometimes I don't know how many rules under with subject and verb agreement, and some prepositional phases, my text book is not that complete and there are some problem in printed materials.

1. Could you help me those basic rules under with subject and verb agreement and for to memorize all those rule and share it to my students.
2. What particular exam do I need to get? would that be TOEFL?
because here in the Philippines when you apply in some companies related for English Teaching has certain requirements. I think I need TOEFL?

Thanks a lot
God Bless
Sanunai