I am not going to be able to write your poem for you, since this is your assignment and your favorite color is not something I can guess! However, I can offer you some help and some examples. I have some ideas on how to create the requisite number of stanzas and some ideas on poetic devices.
One way to create that number of stanzas is to make each about something that is your favorite color. For example, if your favorite color is blue, you can choose five or six things that are blue to write about. You could write a verse about the sky, a verse about the ocean, a verse about a favorite dress or shirt, a verse about someone's beautiful blue eyes, a verse about a blue flower, and a verse about a blue drink that you like. That would be six altogether. If your favorite color is green, you might write about grass, trees, a lime, and a few other green things you can think of. No matter what your favorite color is, there are bound to be plenty of objects or places to write about.
Another way to approach this is to write a series of stanzas on what a particular color makes you think about. For instance, the color blue makes me think about music, the blues, feeling down, coolness, calm, and water. Each of those could have its own stanza, I think. Yellow has a great many associations to it, as do black and white.
There are so many poetic devices that can be used to write your poem. One is alliteration, in which you use the same beginning sounds in words, so that you might write, "Yellow seems like sunny skies." I have three words in that line that begin with an "s," and that is alliteration. Another device is the metaphor, in which you write that something is something else, a concrete image that helps the reader understand a particular quality. If I say "Purple is a king," that is a metaphor, since clearly a color is not a king. I am conveying the idea that this color was used by royalty. Similarly, you can use similes, which are like metaphors, but more in a comparative way, so that you are writing that something is "like" or "as" something else. I might say, "Blue is like the sea." That gives the reader an image in the form of a simile. Another device used in poetry is personification. With personification, I am giving something a human quality, for instance, writing that the "sun smiled down on us." The sun cannot smile, of course, but I am giving the sun that quality for poetic effect. Rhyming is certainly an often used poetic device, and you can devise a rhyme scheme in which all the lines rhyme, in which every other line rhymes, or in which only the last lines in all the stanzas rhyme. I have included a link to our Guide to Literary Terms for you, so you can explore other poetic devices you might use.
This might have seemed like a difficult assignment to you when you got it, but I hope that this will help you see that it is not so difficult after all. And actually, it looks like it will be fun!