Paid Configuration Help

Is there anyone out there that can help me configure my multi-vendor installation to do basic sales from vendors to customers? I seem to have problems with the following:

- Website colours

- Understanding how to upload product (be great if there was a manual I could give to my vendors that show's a simplified process)

- A nice user experience for a customer making a purchase

Any help is very much appreciated. I'm based in Australia so timelines are a consideration.