Designing a banner and logo for my blog

I have a blog entitled "Youth Health 2.0". It is a collection of articles on the intersection of social media, mobile phones and adolescent health promotion. I am currently working on improving the design and layout and require a new banner and logo. I want the banner to say "Youth Health 2.0" and the logo to reflect the tagline: "Articles on social media, mobile phones and adolescent health". I want a round logo so that I can also use it for the website's Twitter profile. Website: [login to view URL]