Using instrumental variables to measure trade policy effects

I'm an undergrad econ student trying to use R for the first time and I'm quite confused as to which script I should use and how to use it. I'm studying the effects of AGOA(African Growth and Opportunity Act) on textile exports of a nation and as such I've been trying to use three types of countries, developing African countries under AGOA, developing African countries not under AGOA and developing Asian countries. I realize I'm asking a great deal, but, if anyone can help me, I would be most grateful.