Open Ultimaker Cura and create a new project by clicking on the "File" menu and selecting "New".
Import your 3D model by clicking on the "File" menu and selecting "Open File". Select the model you want to print and click "Open".
In the "Prepare" tab, select the printer you are using from the drop-down menu.
In the "Extruder" settings, make sure that "Dual Extrusion" is selected. This will enable the use of two different colors.
Select the "Materials" menu and choose the two different colors you want to use. You can add or remove materials by clicking on the "+" or "-" buttons.
In the "Dual Extrusion" settings, you can choose how the two materials will be used. You can set the extruder order, the temperature, and the printing sequence.
Once you have configured the settings, click on the "Slice" button to generate the Gcode file.
After the slicing process is complete, save the Gcode file to your computer by clicking on the "File" menu and selecting "Save".
Finally, transfer the Gcode file to your printer and start the printing process.
That's it! With these steps, you can use Ultimaker Cura to slice a dual-color Gcode file and start printing your model in two different colors.