Hi,
www.dictionary.com is a great place to look up definitions, but I'll give you a really brief and basic overview.
Imagery is the rhetorical tool writers use to creates mental images in a writer's mind by using descriptive words. Denotation and connotation are tricky but fun; denotation is the exact meaning of a word, while connotation is the mood it invokes or how it comes across. For instance, "tug" and "heave" have the same denotation or definition, but "heave" sounds a lot more laborious or hard, which makes gives it a different connotation.
You can find your own examples in the poem (you got this!), but here's a quick guideline:
For imagery, find a line or phrase that is so descriptive, you can almost see it.
For denotation and connotation, find two words whose meanings are similar but that take on different tones.
As for supporting your answers with the Declaration of Emancipation, you'll have to do your research. I'll help clarify, but ultimately, the answer's yours :)
This is an amazing price of art
