Im looking to customise my nav menu\look any suggestions?

Hi,

As the title suggests Im looking to customise the standard Twenty Fourteen black vertical menu at the top of my site. Ideally I want to change the look\colour etc. Now I know there is a plugin to do so but ideally I would like to do something myself.

Does anyone have a link to a demo\tutorial\guide that I could follow through and learn along the way please?

Thanks!