Ok so I just finished reading Lenin's essay on Self-determination and here is what I learned.
1- Self-determination is a nation's right to secede. (Example he gives is Norway and Britain).
2- Socialist from imperial countries such as the U.S should recognize the damage they cause to other socialist countries and not put themselves on a high pedestal.
3- Nationalism lead to the destruction of socialist parties by giving one nation more power than the other. He says that all workers should be united under one goal socialism.
4- A nation cannot have more benefits that another, making its own people better off than others. So Russia cannot give all rights to other Russians while ignoring the rights of other Slavic countries.
If I missed anything or got anything wrong tell me.