let's say I'm analyzing the import of France and it is 100 billion dollars and is divide between 200 countries. how should I gauge where has most of the import come from? top 10? 90 percent of the import? what should be used as a measure here?
If I understand you correctly, you are asking how to find out which countries' exports have most significantly contributed to a given country's (say, France's) imports.
I have recently completed some research on gravity models of trade, and in the process I ended up having to compile various datasets on precisely the topic you are raising.
The United Nations Comtrade International Trade Statistics Database has an easy-to-use interface where you can download bilateral trade data between a "reporter" country (France) and "partner" countries from Rest Of World.
Set the relevant year, set "Reporter" $\to$ "France", set "Partner" $\to$ "All", and set "Trade flows" $\to$ "Imports". Then you can download a cleaned .csv file on which you can run basic summary statistics and do some data analysis (such as finding the top-10 country exporters to France, etc.).
Broadly labeling where "most of France's imports come from" is an ambiguous task. Are you referring to a measure that uses a single country or perhaps a continent? It really depends on what your research question/methodology is. Can you provide some more details?