How i can renewing my domain before Expiration Time ?

and also please answer this question :

1.) If i renew domain before expiration time, what time limit will increase with before limit ?

Example : Now my domain just left 70 Days, if i purchase / renewing my domain it will be

365 + 70 = 435 Days

2.) If we're purchasing domain it possibles to make a sub-domain ?

Example : blog.mydomain.com / blablabla.mydomain.com

1) Yes. But that number is not 70 days, its much lesser than that.
2) Nopes such sub domains are not possible.
It will be something like this.
www.xyz.com/abc-h1.htm

so i can renew my domain before expiration time ?

how i can do that ?

Thx

Should be in the Misc Tab and click renew.