Nickname registration is specific to the network. Some networks do not let you register a nickname, they only allow registration of a username that personally identifies you, and gives you some perks (i.e. user vhost). Some networks do not allow any form of nickname, username or channel registration (i.e. EFnet, IRCnet).
Services have nothing to do with mIRC, nor do registered nicknames or channels. For help with Services, it is better to ask in the network #Help channel as mentioned above (connect to the network, type /join #help) or to check out the network's website for help. The other reason for this is, a whole range of people use this board - some helpers have never come across (and don't want to come across) Services. Others visit differing networks where the commands are slightly different from each other (for example, on DALnet you cannot use /msg nickserv, on another nets this is common). You can get more accurate information from the network users/helpers/opers than you can from this board.