Here’s a perfect example - download the SVG file posted here: Mini electric guitar
Open in your design software.
There are three grouped design elements here - in different colors because they have to engraved, scored, and cut.
Select the “Edit path by node” tool (that’s what Inkscape calls it but other tools have the same tool) and click on each of the three groups of objects. You will see nodes - small boxes - appear along the outline path of each, except for the strings that are straight lines, so they have a node on each end.
To cut and score, you must have a path, which can be created by using any number of tools in the software - “Object to path” for geometric shapes, and “Trace bitmap” for imported bitmaps.
If your file does not have paths (which I suspect it does not), you need to use those tools to create them.
As stated by myself and many others, in this thread and the other you created regarding this same problem, there are many pages of tutorials on how to use these tools. There are also many online video tutorials (search youtube for the tool of your choice.)