As well as relating to a particular Entity, a risk may impact a particular process/sub-process of the organization. To link a risk to a process/sub-process click on Edit in the top toolbar and then click on the Process/Sub-process tab; this will bring up the organizational processes hierarchy.
You can see at the bottom of the screen the process/sub-process hierarchy set up earlier (see above in References Section). Simply click on the relevant process or subprocess within the hierarchy and then save in the usual way.