"By default, the logo area of Slate pulls back the Site Name from the Sitewide Settings section in your dashboard, unless the Site Name stack has been created already - then it pulls whatever content is added in that stack. If you like the look of the logo in the demo and just want to replace 'slate' with your Site Name, simply delete the Site Name stack and update the Site Name section in Dashboard->Sitewide Settings to whatever you want it to be. If you however want to add your own company logo, simply add it to the Site Name stack in Dashboard->Stacks & Blocks.

If the stack Site Name isn't already created in your site, go to Dashboard->Stacks & Blocks and add a new stacked named Site Name. Then simply add a content or image block to that stack with your logo in it.

Note: Most likely the Site Name stack was created during installation of concrete5 and will already include a content block in it with the name of your site in a Heading One tag that is linked to your home page. This will cause the font of your site name to be really huge. To fix this, simply change the text from a Heading One to a Paragraph and remove the link (Slate automatically wraps the Site Name stack in a link to your home page)."

See the rest of the docs here- http://www.c5mix.com/support/documentation/slate/...