Poems are written in lines, which vary in length. The poet chooses the line length to fit the rhythm, feeling, or thought expressed in the poem.
A poem or stanza with one line is called a monostich, one with two lines is a couplet; with three, tercet, or triplet; four, quatrain.
Your poem subject is surface water right? I'll show you something that helped my younger sister, who had the hardest time in English.
Just take a moment to brainstorm everything you know about surface water. When you figure that out, write it out simply. It doesn't have to be special, it could be something as simple as "The top later of the water on the ground." Now try to incorporate more vivid language into that until you've formed a poem! you can do it :) hope i helped