Run Only The furnace fan
You'll need to add a blower relay to your system
Unfortunately, you have an oddball among electric furnaces in that your furnace controls its blower autonomously using the sequencer relay, much like a gas furnace does with its blower thermostat/limit.  As a result, your electric furnace doesn't support a G wire natively.  Fortunately, it's not too difficult to add one on by splicing a fan relay in at the right spot.  In your case, you (or your HVAC tech of choice, if you're not comfortable modding your furnace) need to:

Get a fan relay with a 24VAC coil and SPDT contacts, as well as appropriately sized female quick connects (1/4&quot; wide, and rated for the gauge of wire in question), and some 18AWG TF(F)N in blue, yellow, and green
Install the fan relay in the wiring compartment of the furnace
Move the existing blue wire from the sequencer over to the common terminal on the fan relay
Make up a jumper of blue TFFN with quick connects on each end and use it to connect the normally closed terminal on the fan relay to the sequencer terminal that the original blue wire connected to
Make up a jumper of yellow TFFN and use it to connect the terminal of the sequencer directly opposite the blue wire (it has a yellow wire and nothing else connected to it from the factory) to the normally open terminal on the fan relay
Make up another jumper of blue TFFN with a quick connect at one end and a stripped end at the other and use it to connect one coil terminal on the fan relay to wherever you connected your C wire to
Crimp a quick connect onto a length of green TFFN and strip the other end, then run that from the other coil terminal on the fan relay to where the thermostat wires connect; this will become your new G wire, when wirenutted to the incoming G wire from the thermostat

Once you're done hooking everything up, you can turn the system back on and test operation both with the thermostat fan switch in AUTO and the thermostat fan switch in ON, then enjoy your upgraded furnace!