The concept of "supply chain management" is fairly simple, but the practice can be enormously complex depending upon the size and nature of the company.
Simply, "supply chain management" (SCM) refers to the network of manufacturers, vendors and associated services that aggregately produces a product and places it in the hands of the customer. The more intricate or multifaceted the end product, the more involved the network. The function of the SCM, then, is to provide the most cost-effective way of putting the end product or service with the customer. The process begins with the accumulation of components or materials required for the manufacture of a product and continues all the way through to final distribution.
Preparing an essay on supply chain management should, as with all essays, begin with some measure of familiarization with the subject matter. A good start is the two descriptive articles provided at the links below. As noted above, the concept of SCM is not in and of itself difficult to comprehend. The devil, as usual, is in the details. Certain graphics or charts illustrating SCM in practice can be pretty involved, but, again, that is contingent upon the type of product in question.
Below, in addition to the two articles linked below, is a helpful eNotes article on how to write a research paper. While an essay is not necessarily the same as a research paper—in fact, they can be two very different things—this primer should be useful in preparing an essay on supply chain management. In general, any essay should begin, obviously, with an introduction, maybe one paragraph in length, and be followed by a more in-depth discussion of the subject that includes a definition of supply chain management and any number of paragraphs on the details and advantages or disadvantages of commonly used concepts. Examples of SCM are available by conducting an Internet search using "supply chain management" in the search box. Describing an example for illustrative purposes would add considerably to the value of the essay.