I am assuming that if it is a 6, it is very likely a mid 60s or later, when fuel pumps were common. Thereby, you have a single line fuel hose, with a primer bulb. Go ahead and replace your gas tank with a modern plastic one. Those old metal ones are trouble, and only really useful when a pressure tank is needed.
What gears are you talking about? The shift gears? In that case, put it in neutral.
For cold starting, hook up the fuel line (make sure the arrow on the primer bulb is facing the right way), then squeeze the bulb until it gets solid. Pull out the choke, and commence to pulling. If it doesn't start, and it seems to be flooded, push the choke back in, and give it WOT, then pull it. As soon as it fires, twist the tiller right back down to idle, or it could runaway.
What is the model number of the engine? I need that to find the year, to know a few of the specifics.