Dealing with institutions through 2SLS

[Mustapha Younis]

I am testing the relationship between entrepreneurship and GDP through the effect of institutions on entrepreneurship. The variables I am using for institutions are (government effectiveness, control of corruption, rule of law, property rights, regulatory quality, voice and accountability).

I am supposed to do the first regression of institution variables and doing business on entrepreneurship, then second regression entrepreneurship and all my variables on GDP.

Should I add exclusion variables in 1st and 2snd regressions or the the variables used for institutions are enough?

What are the commands I should be using in this case?

Thanks

[Mustapha Younis]

I need help also in making a regression for all the countries, then make regression for each High income, upper middle, lower middle, low income countries. I have their category already in the data.