here's some general guidelines. its the best i can do. im using realvnc enterprise. ive used them all but pretend your using realvnc free. ya just can't have all the authorities and passwords you said ya didnt have the router. if ya did you need the pass the ports. example of what i have would be virtual server vnc 5800,5900.
my ftp would be 21, 10,000,10010 (this would allow 10 clients) at one time.
take down the firewall. if the remote server is using the ports as mentioned above 5800,5900. you would email him your wan ip. goto whatismyip.com
maybe it would be 99.210.92.151. after starting up the remote software and opening the ports it would be for the client from ie or firefox 99.210.92.151:5800 (this is what you email)
this should give him access. if there was a password involved then he has need to know what it is.
i know its a learning curve. maybe everything your doing is right. just trying to clear the air. maybe your past this part and just getting errors i don't understand. let us know. thats all i got.