The wiring diagram for your model of dryer is illustrated below in the first image. If the igniter is not glowing, then I recommend checking the thermal fuse first. Follow these steps to check this component:
Unplug the dryer to completely disconnect electrical power.
Shut the gas supply cut-off valve to the dryer.
Remove the bottom front service panel as shown in the second image below.
The thermal fuse is located on the blower housing (Key 59 in the third image below). Pull the wires off of the thermal fuse (with the dryer still unplugged). Measure the resistance across the leads on the thermal fuse using a volt/ohm meter. You should measure near zero ohms of resistance. If you measure infinite resistance, then the thermal fuse is blown and will need to be replaced.
NOTE: If the thermal fuse was blown, check your venting in the dryer. Clogged or restricted venting could cause the thermal fuse to blow.
If the thermal fuse is okay, then check the high limit thermostat (Key 43) that is on the side of the burner funnel in the same manner. If the high limit thermostat measures infinite resistance (instead of near zero ohms), then it will need to be replaced.
If both of these components are okay, check the thermistor (Key 42) next. The thermistor provides a temperature reading to the control board. If it is defective, it could prevent the dryer from heating. The procedure for measuring the resistance of the thermistor is the same as the above 2 components. The thermistor should normally measure around 10K ohms (10,000 ohms) at room temperature of 75 degrees F. If the thermistor does not read near this resistance, then it is defective and would need to be replaced.
If all of these components are okay, I recommend measuring the resistance across the igniter. The igniter should measure between 50 to 500 ohms of resistance. If it is defective, it would need to be replaced.
If the igniter is okay, then the flame sensor would need to be checked. The flame sensor should measure near zero ohms. If it is defective, it would need to be replaced.
If all of the above components are okay, then you could have a failure in the heater relay or the control board. You could also have a wiring failure between components. Loss of the neutral circuit through the motor centrifugal switch could also prevent the igniter from glowing. These types of failures are normally diagnosed only by a service technician. Live voltage measurements would be required while the dryer is running. I don't recommend taking these types of readings yourself. If you are completely confident in your technical ability to safely make these type of checks, resubmit your question with additional details for more help with this dryer problem.