Magento add manufacturer

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To add manufacture attributes

Login to admin panel goto Catalog >> Attributes >> Manage Attributes from the list of pages.

Select Manufacture Attributes, and you can set Manufactures form there. Manufacturer attribute should be assigned to a product attribute. If Magento manufacturer attribute is created, we can add new manufactures name.
For Logo Make a directory in media >> catalog >> brands and put your logos in there. Logo can be jpg, png or gif. Manufacture Logo named should be manufacturer attribute with underscores used for spaces.