Banner design minimum 2 banners required

I am looking for a talented graphic designer to design two banner designs for me. The banners should be of a modern look and feel, and should be in the following sizes: small (300x250px), medium (728x90px) and large (1600x900px). They can be used on my Facebook page and other social media applications. I don't have existing branding materials to incorporate, but I am open to any ideas the designer might suggest.