Hi, I would like to create a custom line type but I don´t have any experience doing that. Can anyone help me with this?

Line type should be 2 lines (lineweight 0,18 mm) parallel with distance of 0,6. I am using a Metric measurement system (for line types and hatch patterns).
This line type is going to be used for drawing curbs. I appreciate any help with this since I have also zero experience with coding.
