With poetry a good starting point is always to try and relate what the poem is about to your own life. One way to tackle this poem is to think about your own life and consider a choice that you made that marked a real turning point in your life and the way it was going. It might have been something simple or something big, for example if could have been trying out for a sports team, standing up for a friend or a job choice. However, now, because of that choice, your life has gone in a completely different direction as a result. Go back to the moment when you made the choice, and imagine that you made a different one instead. How would your life be different now? What would you be doing?
This poem is symbolically about these kind of decisions, as the persona of the poem takes a walk in a wood and is confronted with this kind of choice:
Two roads diverged in a yellow wood,
And sorry I could not travel both...
This poet has to make such a decision, chooses one, with the intention of going back and taking the other, however he admits that:
Yet knowing how way leads on to way,
I doubted if I should ever come back.
This choice therefore captures the theme of the poem which could be said to be contradictions. A particular choice you once made might have improved your life in some ways but made it worse in others. Was it a good choice or a bad one? It was both - and it was neither. Yet the last stanza makes it clear that this relatively simple choice is one that the persona knows will haunt him in his later life as he thinks what his life would be like if he had taken the other path:
I shall be telling this with a sigh
Somewhere ages and ages hence:
Two roads diverged in a wood, and I -
I took the one less travelled by,
And that has made all the difference.
In this poem therefore the roads and the choice that the poet needs to make stand as symbols for the choices we need to make in life. The last line of the poem recognises how even the simplest of choices can have a massive impact on the course of our lives, and the last stanza makes it clear the way that these life choices can haunt us as we consider what would have happened if we had taken another path. What could have happened if...? Where would I be now if I had chosen differently?
Hope this helps!