I am new to writing reviews, I would like to submit review for a new provider from a agency, how would I do this ?.

...agency/driver/independent, choose "agency."  For the website, link to the provider's ad on the agency website; do not link to the agency's home page.

You just indicate on the review that she is from an agency.  If she has no reviews, you will set up her profile, and admin will assign her an ID number, just like any other new provider's review.  Read the rules on writing reviews before you do it.  Read the self help center too.

Your review may not get approved unless and until another, more experienced reviewer, submits a review as well.

I am not saying this as an absolute, just don't be surprised if it takes quite a while for your review to be approved, if at all.

Thanks a lot for the information.