From this and your other question today I get the impression you are confusing domain names and trademarks. A domain name can incorporate a trademark, but merely registering and using a domain name does not automatically give you any trademark rights in that domain name. To gain trademark rights, and to be able to exclude others from using the same or similar mark, the domain name must function as a trademark. If your domain name only appears in the internet address bar of your website, that is not enough to act as a trademark. However, if the domain name is prominantly displayed on your webpage, such as in the header or banner for the website, it could function as a trademark. Furthermore, trademark rights are gained through use of the mark in connection with the sale of goods or services. Until your web business is actually up and running and you have sold your services, you have not acquired any trademark rights.
That being said, if your domain name does function as a trademark, and certain conditions are met, you may be able to exclude others from registering similar domain names. Only an attorney knowing more details about your business can answer this.