How did the truman doctrine prevent communism from spreading?

Ineed with what i should write for my research paper. my topic is history of slavery. 1800 words. all i need is what to write in each paragraphs. like when the research paper has titles for each paragraph and it explains the tile in each paragraph. for example when did slaverh begin? why did it begin like an outline.

List two inventions that were invented in the united states before the american civil war

Why did stalin want control of eastern europe after ww2?