To add a filter, select the 'Filter→Add filter..' menu option, or select the 'add filter' toolbar button shown below:

This will open the 'add filter' window, shown below:

To add a filter, simply select it from the tree list, and press the 'add filter' button.

For more information about each filter, please see the filter reference page.

To delete a filter, select the filter by left-clicking the mouse on it, then select the 'Filter→Delete' menu option, or select the 'delete filter' toolbar button shown below: