When annotating a poem, it really depends on what you are looking for.  There are several elements you can choose.  I suggest annotating for style, literary devices, and diction.

Since this poem is written in a unique style, I would start there.  I like to use different colors when annotating.  Let’s select yellow for style.  I will fist highlight all of the punctuation in yellow.  Do you notice something?  Look at the first line.

Life, death, - death, life; the words have led for ages

The first thing I notice is that by putting double punctuation after the first “death” the poet creates a kind of stream of consciousness.  The poem becomes like a thought.  It is internal musings. The dash appears again before the last line.  It therefore sandwiches the poem, making the middle lines seem like an aside or a train of thought.  What other stylistic choices do you see?

Second, we will annotate for literary devices.  Do you see the rhyme scheme? 

Life, death, - death, life; the words have led for ages
Our thought and consciousness and firmly seemed
Two opposites; but now long-hidden pages

The last word in the first line, “ages,” rhymes with the last word in the third line, “pages.”  Also, the second and fourth lines rhyme.  Try underlining words that rhyme with another highlighter color.  You will notice that the rhyme scheme is ABABCC, which is iambic pentameter.  This gives the poem that “heartbeat” sound, making it seem all the more rhythmic and persona. 

Finally, let’s look at diction, or the word choice. In addition to rhyme there is a metaphor, comparing thoughts to pages.  The choice of words like “undreamed” is an interesting one.  What are “liberating truths undreamed” in this case?  It makes the reader think about chances we might have had.  Do you see other words chosen carefully?