how to play with people without...?

why do you mean by use hot-keys to launch the server and can you tell me what key to press?

I think its: F4 and then F5 when you selected the gametype

omg, go on friend list , over your friends name, click on the small arrow and select Join Match

thank you i will try

This is because your nat settings might be wrong.

1: This happens to me when I am at my dad. Even when the nat is open.
When i am home it's also open but they join me fast. max 5 min waiting.

2: Friends also help others to connect to your server.
because this won't make the match end so fast and you won't have to restart.
Restart means that your "server" /game will get lower on the game list.
(For players to connect.)

Go in the Game with mw2 liberation and click on find game or something like that xD then choose like team deathmatch and press F4 to choose map and game settings and all that if ur finished press F5 and ur ingame now u need to wait some time to get players in if u waited some time and u dont got players press ALT+F2 to refresh the lobby

You learned how to copy and paste today?
Read above and you see almost the same, just other gametypes....

Let me notice you on something here:
When you hack MW2. Change your stats or get a to high KS.
You won't get so easy in other matches. This happens to many others.
And might as well be what he experience now. He is on a own server/list of over- powered/stated players.