You need to register your brand firstly.
When you're ordering more than 1000pcs for a model, the factory could put your brand logo, your brand manual, your brand packing,etc. for you.
You can also order 100pcs with your own brand, but you need to pay more on the logo making, manual, packing,etc.
As long as you're not ordering conterfeit/fake brand named MP3,MP4, you will have no problem to get through the customs, even without any brand.