Help Apostrophe and Possession

[Mosiuser]

Dear all,
I have been struggling to understand to differentiate the uses of an apostrophe in possession and noun-extended adjectives for possession. Sorry, I have confused them but try to get the idea of my problem.

Examples
1: Africa Cup of Nations, African Cup of Nations or Africa's Cup of Nations.

2: America Best Championships, American Best Championships or America's Championships

3:Africa Continent, African continent or Africa's continent

4:Nation Newspaper, National Newspaper or Nation's Newspaper

I will appreciate if I get clarifications on the problems with regards to the examples above
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