You have to let search engines know that you exist as a first step. This is done by either going to them and submitting your domain to be spidered, or by linking with other websites so that the search engines can follow the link and find you. In either case, once Google (the people who created the sandbox) find your site, you will then be placed into the sandbox. This means you won’t be able to achieve rankings for your site for competitive terms. The sandbox period typically lasts for 6-8 months, though many people claim it can be longer, as much as 18 months.