You will need a sign-up form on your Thesis Theme site that asks for your visitor’s email. There are several widgets that will handle this task for you. Widgets are for blog based sites so if they don’t fit your needs then there are other programs and code to choose among. Even better, Thesis Theme sites that have good information are very easy to build a list for. As long as the form is visible people will give you their email addresses. Once you become known in your niche as an honest person that has something to offer then people will seek out your site in order to become a subscriber. Offer an incentive for signing up for your list. Nothing else works as good as this method, and if you offer something very useful then they may even stick around for a long time. The most common item to give away is an e-book or short report. You would be surprised at how often people will give away their e-mail addresses to get something for free. A variation on the free download is to offer a coupon code for Thesis Theme itself. People love this and will appreciate you for it.