The arms dealer job:
So,the job is located behind the casino in Montgomery.You can see a deagle icon on the map.Go there and type /getjob to take it.With this job you can make weapons and Ammos(bullets) for the weapons.From where i can make the weapons?Go to Marvins hardware,it's located infront of the news corp. in Montgomery.You can see a big signatue with the text 'Marvins Hardware'.You will see something like a yellow '?' when you arrive(Not on the map).Go on this icon and it will appear on your screen what you have to type to make weapons.What i need to make weapons?You need only Materials and Cash.
What i can make?You can make 9mm's,Shotguns,MP5,Desert Eagles,Ak 47 and Country rifle.
How i can make Ammos.(bullets):You can make them with Materials and Cash as well.
Well,i hope i helped you with this tutorial.I don't remember on which level what you can make,because i was an Arms Dealer only once.