This probably means that the choice is yours. Your the author of the script of your life because you get to write your own story and make your own choices. Your the captain of your ship for the same thing. You sail wherever you want to lead your life too/
This is not a question this is negative
Robert Frost's poem has the structure of a lyric poem. If you think about it, this poem could be put to some music and be sung, just like song lyrics.