There are a couple of ways to do this depending on the need.
1) Select a section in the content tree, on the 'General' tab of the section details, highlight the section name and using the 'Font Color' drop down select a colour. This will apply for the particular section.
2) On the Design Tab click on a Section name in the preview and then using the 'Font Color' drop down select a colour that will affect all section names over the site.
1) Select a section in the content tree, on the 'General' tab of the section details, highlight the section name and using the 'Font Color' drop down select a colour. This will apply for the particular section.
2) On the Design Tab click on a Section name in the preview and then using the 'Font Color' drop down select a colour that will affect all section names over the site.