After creating the brands you require, you need to specify what products in your store belong to which brands. That is done by assigning the brand names to specific products as attribute values.
To assign a brand name to a product:
Find the product you require and open its details for editing.
Switch to the Attributes tab of the product details and choose to edit the product's Global attributes.
Locate the global attribute field that you have chosen to use for product brand information (for example, "Manufacturer") and adjust its value by selecting the brand name you require.
Click Save changes.