Joomla 1.5 Web site modifications

I have uploaded a Joomla site and require the addition of 15 article backgounds, modifications to the header logo and changes to overall site in line with a proposal from a design company. This design from the graphic artist is in powerpoint format, and we need to change the joomla site to be as close to the design provided. I have background images and articles created already, and images will be provided. The site is already uploaded to a temporary url so its available online. I will supply username and password. This way I can review changes easily. I iwll send the powerpoint to bidders and temporary url is [login to view URL] Once the site is done, I will need SEO implementing. Thanks.