You can confer some of your site's reputation to another site when your site links to it. Sometimes users can take advantage of this by adding links to their own site in your comment sections or message boards. Or sometimes you might mention a site in a negative way and don't want to confer any of your reputation upon it. For example, imagine that you're writing a blog post on the topic of comment spamming and you want to call out a site that recently comment spammed your blog. You want to warn others of the site, so you include the link to it in your content; however, you certainly don't want to give the site some of your reputation from your link. This would be a good time to use nofollow.
After that, you need to make a choice about how to construct an online presence that helps you achieve that goal. Maybe you need to set up an e-commerce site. If you’re interested in publishing content to drive awareness and subscribers, look into setting up a blog. A simple website or landing page with a lead capture form can help you start developing your brand and generating traffic. A basic analytics platform (like Google Analytics, which is free) can help you start to measure how you are tracking towards your initial goal.