This might/might not help. Always lots for a beginner to get a handle on 
Shows 3 options.
1. Ofnuts text along path plug-in
2. The question you asked, how to break up a circular path into an arc.
3. An alternative, use a circular selection as a template, and trace a path along the (temporary) selection.
direct link https://youtu.be/7fumw57Z2H8 duration 5 minutes
Shows 3 options.
1. Ofnuts text along path plug-in
2. The question you asked, how to break up a circular path into an arc.
3. An alternative, use a circular selection as a template, and trace a path along the (temporary) selection.
direct link https://youtu.be/7fumw57Z2H8 duration 5 minutes