The document says you add custom filters on shortcode
try adding
[civievent_widget custom_filter='{"start_date":{"IS NOT NULL":1},"id":{"IN":[9,10,11]},"is_public":1,"options":{"sort": "start_date ASC"}}' admin_type="custom" custom_display='{"event_title_infolink":{"title":0,"prefix":null,"suffix":null,"wrapper":1},"description":{"title":1,"prefix":null,"suffix":null,"wrapper":1}}' limit=5]
Also you will need to amend the patch below to decode html entities
diff --git a/civievent-widget.php b/civievent-widget.php
index e973ce0..c3c2da4 100644
--- a/civievent-widget.php
+++ b/civievent-widget.php
@@ -223,7 +223,7 @@ class civievent_Widget extends WP_Widget {
$standardDisplay = true;
} else {
// Get custom filters.
- $customFilters = json_decode( CRM_Utils_Array::value( 'custom_filter', $instance, '' ), true );
+ $customFilters = json_decode(html_entity_decode(CRM_Utils_Array::value( 'custom_filter', $instance, '' )), true );
$filterParams = array(
'start_date' => array( '>=' => date( 'Y-m-d' ) ),
'is_public' => 1,