Below are the steps how to get for free renewal domain name on CO.CC:
1. Sign in to your account at CO.CC
2. Choose a domain name in experied who want to extend more active period
3. Click Renew
4. Select / Personal check (renewal fee: $ 0/year), check also lower
5. Click Continue
6. Done. Wait in the 1 × 24h domain / blog you will be loaded again as before
For screenshoot, please see below:

If you don’t have account on CO.CC or maybe you want to get one or more domains from CO.CC, you can …

Many blog owners use co.cc domain besides free, it also less of restriction. But, do you know co.cc domain has period for expired?
co.cc just give you free domain only for 1 year. After that, we have to extend co.cc domain with charge. But, there are some of the co.cc domain is still able to use although already in use more than 1 year. However, there are also domain co.cc that less than 1 year has expired and can not be accessed.