Working on the chute now... That'll free up an extra guy. How do I set up the minecart?
To set-up the track you are going to want one of two options. The first is to build the track (as a construction) and the second is to carve the track (into stone, through the designation menu). If you have a stone floor, carving the track is what you want.
I'm not sure how you're oriented, but let's assume that your track is running west-east with the chute at the east end.
S=hematite stockpile
-=track
X=track ends
O=chute
SSS
SSSX----------------XO
SSS
Once you have that completed, you're going to go 'b' 'C' and built Track Stops on either end of the track. These are going to require a dwarf with the mechanics labour enabled, but it will not require mechanisms, so don't worry about having to have any of those on hand. So your track will then look like this.
S=hematite stockpile
-=track
Q=Track Stop (construction)
O=chute
SSS
SSSQ----------------QO
SSS
When you're building the TS at the end point closest to the chute, you will see that there is a little bit of information in the sidebar while track stops are being placed. It will talk about friction and dumping, and by default friction will be at its highest point (stopping the minecart) and automatic dumping will be disabled, thus forcing a dwarf to come by and dump the minecart's contents himself. You don't want that, so hit the 'd' key until it says to automatically dump its contents on arrival to the east. This will then dump everything in the cart into the chute one square to the east of the track. The default settings can be left as is at the 'input' track stop.
Congratulations, you've built your first minecart track! However, it won't do anything yet besides sit there and look pretty. This is where the hauling menu 'h' comes into play. Create a new route, and then define stops on the route by pressing the 's' key first on your input track stop, and then on your output track stop. It'll give you yellow exclamation mark warnings at the start because the direction is incorrect. Highlight the stops and hit enter in order to edit them. You'll want to hit the 'd' key to change the direction you want the minecart to travel when it leaves that stop. So since the first order will say to 'Guide North immediately when full of items', you want to hit 'd' until it says 'East'. You can also hit 'p' to change it from guide mode to push mode. Guide mode has a dwarf pushing it from behind along each piece of track, while Push mode a dwarf comes along, gives it a shove, and the cart goes down the track until it reaches a track stop with high friction or hits something that makes it stop. You've now set the direction you want it to go when it's full, but the route doesn't know what it's supposed to be hauling. You then have to make a stockpile link so that it knows from which stockpile to take from. Press 's', then move your cursor to highlight your hematite stockpile, and hit 'p'. That makes the link. Then hit enter, and pick out hematite and/or any other ores or economic stones or whatnot that you want the minecart to take. Now hit escape to return to the main hauling menu, cycle down to stop 2 on your route, and hit enter to edit it. Hit 'x' three times to delete the conditions, then hit 'n' to add a new one. Change the direction to 'west', and you can either have the dwarf guide or push it.
Now your track is setup with all of its orders, but you still need a minecart for it all to happen. Go back to the main hauling menu and highlight your route. Press 'v' to assign a vehicle, scroll until you've got the minecart that you want (you'll need to have one built previously out of wood from a carpentry shop or metal from a forge), and hit enter to assign it. Your dwarves will the haul the vehicle to the input stop, and then start filling the cart up with the desired items from the input stockpile and sending it on its merry way. Bonus: you now have a quantum stockpile of hematite.
Make sure that there is an appropriately designated stockpile at the bottom of the chute, though, or else your dwarves will start hauling what just fell 100 z-levels back up to the input stockpile, loading them into the minecart, and sending them down the shaft again.