If you want to transfer a domain, then you need to initiate it from the new registrar. Normally, you should be presented with the necessary steps. Make sure you unlock the domain prior to transfer initiation, and lock it right after it. A transfer should take a max of ~7 days.
If you simply want to change hosts, then all you really need to do is to change nameservers.
"Free" domains that come with 1 year prepaid hosting plans are often registered in the name of the host, so that customers don't abuse the service by signing up, getting the domain for free, tranferring it to another registrar, then asking for a full refund from the host. Instead, the host keeps the domain under its direct control, so that early cancellation will result in a subtraction of the domain registering fee, followed by the release of the domain to the ex-customer. Check the terms of service carefully.
>> getting the domain for free, tranferring it to another registrar, then asking for a full refund from the host.
sorry, not quite understand this step
How long have you stayed with your hoster? If you have paid for a year and now want to switch hosts, it's natural to ask for refund, but in this case, you won't get your free domain. If your payment period is almost over, then I see no reason to worry, just make sure it's registered in your name.
are there cases that the host refuse to release the domain in order to keep you as their customers ? don't want to let you go ? thanks
Yes, there are, unfortunately.
Most "free" domains with a web hosting account are not owned by the account registrant. A quick of a "whois" will tell you who owns the domain name. It's usually the web host.
I have a client who is in danger of losing all of his hard work because he cannot get his previous host to renew his "free" domain name, because he doesn't have a web hosting account there any more, even if he offers to pay to renew the domain. They won't take his money. And they won't help him transfer it away. It's absurd. But absolutely true.
To make matters worse, it's an ENOM reseller account.