1) The gray background needs to be changed. Black text on gray background makes it hard to read.
2) Good Logo, but it may be more recognized with a heart on it somewhere
3) Use RSS feeds from the top health and heart websites or news organizations to your home page.
4) Decide on 4-10 tags that you are going to build into video sections around cholesterol and heart health. Then add 5-10 embedded videos from youtube daily using searches to find good vids. Use unique titles and descriptions. This will help you on the search engines.
5) Promote your videos front and center on your home page. People with health issues eat up information. This will be your hook in the beginning while you are trying to build your member base.
The bottom line is that social networks do not real start clicking until you are getting 30-50 new members daily. While you are working towards that you need to be building out your content daily. This will increase page views of your current visitors and will build your traffic from organic search results.
SUp.biz, COO has given you excellent suggestions,you can follow these.
Let me introduce my self, vSplash offers small business web design , custom e-commerce website development solutions. Search Engine Optimization (SEO) services offered by us help you to get high-quality traffic to your website from search engines.