You may not transfer a domain name for 60 days after its purchase or for 60 days after you change any registrant contact information. This is a rule set by the Internet Corporation for Assigned Names and Numbers (ICANN) and standard across all registrars.
This guide explains how to transfer the domain name to another registrar.
To point the domain you registered at WordPress.com to another server (hosting service), please follow the instructions here:
http://en.support.wordpress.com/domains/change-name-servers/#changing-domain-name-servers
Note you will need to obtain the name server values from your current host. You should be able to find them on their support documentation, or contact them and ask for the information. (Name servers may be referred as "nameservers" or "NS records" instead.)
Hope this helps - let us know if you have any more questions!