Due to privacy protection you might not be able to see registrant contact details. However still you can check other details such as domain registration ,expiration date, host name etc. Also any Register.TO user can easily contact the owner of .to domain if the domain you are searching is being managed on register.to platform.
To start first visit this Register.TO Whois search page here.
Now enter the domain name and click on Whois Lookup.You'll see different details related to domain such as Domain Host Name, Create Date, Expiry Date etc.
If you want to contact the domain owner to purchase the name or for any other reason you can do so by clicking on hyperlinked text below the domain details. Don't spam this feature otherwise your IP might get blocked by admin.You'll be taken to the page where you can submit your email address.
Once you submit your email address, it will automatically notify the domain owner via email about your interest. There is no option to type message.
From here domain owner has freedom to contact you. I tried to contact one of my own domain and got following message from Register.to via Email.
Greetings Register.TO Customer,
Another Register.TO user (email@example.com) has requested that you contact them regarding your registration of 'XXXXX.to'.
You are under no obligation to contact them. A posssible reason for contact may be to purchase the domain from you.
I hope this article was helpful.