This is really ennoying me now ive tryed my best to install everything by the correct instructions but when i press the connect button it says this...
[10:53pm] * Connect retry #45 123.456.789.123 (6662)
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[10:53pm] * Unable to resolve server

how do i solve this problem?

SOME ONE PLEASE HELP I REALLY WANNA DOWNLOAD A FILM

We don't help you download films with mIRC. In all probability, you don't hold a licence to the material.

but i am registered though

Registration doesn't make it legal to download illegal materials like movies.

Note that if you can't connect and are getting that error, then either you are trying to connect to an invalid server address/IP or else you have a router or firewall or antivirus blocking you from connecting. There are many posts about dealing with those things, if you use the search feature in the forum. http://www.portforward.com is a good place to find out how to forward (open) the ports needed.