What part of the tree contains the seeds?

This depends on the type of tree....but a general answer is: on a fruit or nut tree the seeds are inside the fruit, in the nut, the little seeds a pinecone. Or they may be carried in a windborne string or cottony material. Look up the type of tree.

Most trees can be started from a cutting, but it should be researched..ask an expert at a University Extension office. This is their job and they love to help.