I have opened a step in a workflow, but the New entry is grayed out / Disable.

Usually this is due to settings in this workflow step. Inside workflow step there is a setting "New entries can be created in this step"

If you have rights to change settings on your workflow, you can click on the step in the tree structure and select Settings to change this setting. 
If not then you can contact the administrator who can possibly change this setting for you.