@patel Connecting the two motors to the ZA and ZB driver connectors individually connects them in series. So you should set the current as for one motor (though both motors should be the same). Set the current between 50 and 85% of rated current, so between 800mA and 1400mA (we round down to the nearest 100mA).
you also get that message if you home against limit switches (for example on a delta at the top) without homing with the Z probe. My Z switches on my delta is good enough for me not probing with BLtouch each time so I get that each time I don't do a probe run before loading the height map. It's not a error it's just a warning telling you that the height map is based on the Z datum set with the probe and not the limit switches you home against.
Vfan jumper has 3 pins. One is always +5v from the 5v regulator on the duet (or possibly external 5v if you have that jumper set). One is Vin from your psu so 12 or 24v usually. The jumper connects the fan positive bus which runs to all the fan headers both pwm and always-on, to either 5v or Vin depending on the jumper connection.
So chose one.
However you can be clever with it. I have some 5v fans and some 24v fans. The 5v fans positive comes off the +5v pin of the vfan header and are grounded via the fan header GND of your choice. The pwm is achieved through the gnd. The rest of my fans plug into the fan headers directly and my vfan jumper is set to Vin (I have a 24v psu).
You can also have 12v fans on a 24v system by connecting 12v to the central pin of vfan header.
I don't know about other modems but my BT Home Hub has a check box to "Always use this IP address" for DHCP devices. So although it's initially assigned as IP address from the DHCP pool, thereafter it will always use that address which is handy.
If you still don't undersand it ,then ask what the problem specific is and you will get help fast here.
But you can't expect people will write down the whole procedure for you here on the forum,
if it is nicely explained in the wiki.