Okay, so unsure where to start here.
Basically after having virtually no problems with gaming online one series seems to be eluding my internet capabilities (which aren't very good) : Call of Duty.

After buying MW2 upon release whenever it was released on my PS3 I immediately was confronted with 'Servers are unavailable, please try again later or visit the Call of Duty website'
Even weeks after release, the problem persisted. I had an xbox around this time and the game worked perfectly on that format.
Long story short; Black Ops, MW3 and now Black Ops 2 all have the same problem.
(Only now the servers are smaller so MW2 and Black Ops 1 both work online now, MW3 and BO2 do not.)

Everytime I attempt to play MW3 or BO2 I am confronted with the same, 'Cannot connect to server' etc.
I am told there are solutions to my problems by various methods, forwarding ports, opening NAT, etc.
But truth be told, I know nothing of these methods because I'm the furthest from technical you could imagine.
I just rang my provider (Orange) and the call centre wasn't my country so I couldn't understand, and I could not be understood, the gentleman said a little about ports, then kind of lost confidence in what he was saying and abruptly hung up.

I really need to get this sorted as now I have more free time I'm becoming a more serious gamer, I have not just paid 40 to play a campaign, after all.

I am with orange on a Netgear N150 wireless modem, router DGN1000
I've currently entered my I.P thing into the address bar to get onto the connection settings and right now I REALLY would appreciate someone to hold my hand and help me through the rest of this!

PS: My signal is as weak as cats P*** so I currently have an Ethernet cable running from the router upstairs and directly into my PS3, from which I am recieving a Type 2 NAT connection.

tl;dr: ports need opening, need better NAT, to help COD work? or maybe theres something else I can do, any help will be appreciated.