Brand new user with Formbot T-Rex 3D printer

I just downloaded Lightburn to try because Dragonfly 1.7 that came with my Formbot T-Rex 3D printer is worthless.
I plugged in my 3D printer and had the program look for any compatible lasers but nothing. So now I need to know what to do. Normally, I would place the gcode on an SD card and insert that into the machine. Hit run from SD card and the laser does its thing.
Where do I find information on how to my particular 3D printer with lightburn?
I am assuming that I would go into creat manually, select one of the GRBL models, but which one?

A quick Google search shows that 3d printer uses the very popular Marlin firmware.

You might find what your looking for here:

https://forum.lightburnsoftware.com/c/hardware/marlin

Thanks for the response. I tried Marlin and it controls everything but the laser on and off. I was able to home (how ever my machine homes to the center of the build platform and that is not an option) after some trial and error. When I run the gcode it looks as if it is doing what the preview shows but the laser never turned on.
I am doing a search for that but if you have a link I would appreciate it.

How is your laser connected? (IE, to which fan port?) Depending on your build, you might need M3 / M5 commands, or M106 / M107, and/or a different tool index. Both of those can be set in Edit > Device Settings near the lower right of the window.

Thank you for the reply.
I just found the M3 M5 by looking at the old file from Dragonfly and changed in the settings. Now the laser turns on and fires at the correct times, I am assuming because it is not burning anything into the wood. I am trying to increase the distance from the wood, manual focusing, increasing the power, etc.