There are many activities involved in materials management, and I've provided some links that I hope will help you with this area.
One important aspect of materials management is purchasing. Someone must decide what what needs to be purchased, make a choice among providers, and order in sufficient quantities to allow the proper amount of production. This requires research and planning. Factors that must be considered are price, quality, quantity, availability, the reliability of the provider(s), credit terms, and shipping costs.
Another important part of materials management is inventory control. This can include raw materials and what are called "work-in-process" pieces that are incomplete products, for example, the various components of a computer, which are made from raw materials, but not yet part of a complete computer. Good materials management means having sufficient inventory of raw materials to create works-in-process or finished products, without slowing down production, but not having so much inventory of materials that there is too much money tied up in the materials when they are not being used for production and without having to worry about the cost of storing materials that are not being used in the near future, particularly materials that can deteriorate or that require special storage conditions.
Another aspect of materials management is scheduling. Someone has to make sure that materials are where they are supposed to be when they are supposed to be there. An assembly line that cannot assemble because the right materials are not there is a great loss to a manufacturer. People must be paid, and the consumption of utilities is not producing products.
There are other activities in materials management, but this should be a good start.