All in green went my love riding on a great horse of gold into the silver dawn.
The poem starts out pretty clearly: the speaker's love is horseback riding early in the morning (around dawn). And Cummings conveys this to us to us in pretty simple language: three lines which use very few words. If this were Scrabble, Cummings would still have lots of tiles to play.
But even in short lines, Cummings packs the scene with colors, colors, colors. It's like we're walking (or, more precisely, reading) our way into a picture. Between the green clothes the rider wears, the gold horse, and the silver dawn, it's pretty clear the Cummings is going to be emphasizing visuals in this poem. After all, we don't hear or smell anything as we read. Instead we see it all—just in like a painting.
Also, check out the ways that the syntax twists around in the beginning of this poem. In American English, it's usually the case that the subject comes before the verb. But in line 1, subject and verb are reversed. It's just like in Ye Olde Englishe. Right from the beginning, Cummings is building up a Renaissance-y feel. It's almost like weaving an historical tapestry.
Notice, as well, that lines 2 and 3 both begin with a preposition—which is a fancy term for a word that indicates the position of the noun in relationship to everything else in its world. In this case, the prepositions are "on" and "into." Cummings is laying out a setting, and he does so by underscoring how each of the lines moves us more and more specifically into the scene. (Check out "Setting" for more.)