Once installed, depending on the plugin, you might need to specify some global settings:
Once an plugin has been successfully installed, it can be assigned to one (or many) fields in one of your models. To do that navigate to a Model, select a field and navigate to the Settings > Presentation tab of the field.
If a plugin is a field editor or a sidebar widget — and the plugin is compatible with the type of field you've selected — you will be able to select it and setup any configuration options:
If the plugin is a field addon — and again, if the plugin is compatible with the type of field you've selected — you will be able to add it and configure it as well:
To use the plugin across several fields, just repeat the above steps again for each field.