Good Day everyone
I am fairly new to Stata, so my apologies if my question is rather redundant.

I would like to analyze the effect of Sanctions of the European Union in year X on Trade flows between two countries (A and B). (for year X+1 and X+2)
(Country B doesn't sanction country A)
As raw data, I have 3 separate cross-sectional data of the trade flows of all countries worldwide. (year X, X+1, X+2)
The goods are separated into different categories, some of those are Sanctioned by the European Union, some are not.

My aim is to analyze, whether country A and B trade relatively more with each other in years X+1 and X+2 in goods, after the Sanctions went into effect in year X, that are sanctioned compared with those that are not.sanctioned

Now since I am now to the program, in my attempts to analyze this I have encountered several problems, maybe one of you could be so nice to help out with these issues.

a) How would you use the three different datasets (for years X, X+1, X+2), would you just append them or would you suggest a better alternative?
b) I am unsure about the amount of dummy variables that I should create. (Currently I have dummy for (1) Sanctioned goods (2) country A (3) country B. Would you suggest to create others?
c) How would you attempt to analyze the difference of Sanctioned goods to Non Sanctioned goods?
If the questions are too basic or unclear my apologies again

I would be highly glad for any help