To register a trademark in India online, you can follow the steps outlined below:

1. Visit the official website: Go to the website of the Controller General of Patents, Designs, and Trademarks (CGPDTM), which is the regulatory body responsible for trademark registration in India. The website address is http://www.ipindia.nic.in/.
2. Create an account: If you don't have an account on the website, create one by registering as a user. Provide the necessary details and follow the instructions to set up your account.
3. Fill out the application form: Once you have an account, log in and select the option to file a new trademark application. Fill out the application form with all the required information, including the name and address of the trademark owner, a description of the goods or services associated with the trademark, and the trademark representation (logo or wordmark).
4. Conduct a trademark search: Before applying, it's advisable to conduct a trademark search to ensure that your proposed trademark doesn't conflict with any existing registered trademarks. The online portal provides a search facility to check the availability of your proposed trademark.
5. Pay the application fee: After filling out the application form, you need to pay the application fee. The fee varies depending on the type of applicant (individual, small enterprise, or others). The fee structure can be found on the website.
6. Apply: After making the payment, submit your application online. The online portal will generate an acknowledgment receipt with an application number.
7. Application processing: The trademark office will review your application and issue an examination report. If there are any objections or deficiencies, you will be notified, and you will have the opportunity to respond within the specified period.
8. Publication in the Trademark Journal: If the examination report is satisfactory, the trademark will be published in the Trademark Journal. This allows third parties to oppose the registration within a specified period.
9. Registration: If no opposition is filed within the stipulated time or if any opposition is successfully overcome, the trademark will proceed for registration. You will receive a registration certificate upon successful registration.

It's worth noting that the process of trademark registration can take several months or even years, depending on various factors, including the backlog of applications and any objections or oppositions raised during the process. It's advisable to consult a trademark attorney or agent for assistance throughout the process to ensure proper compliance and increase the chances of successful registration.