// This is for a SINGLE email to all recipients in your list

// From your query results, assembled string that holds the email
// addresses to which you are sending the email.
String[] toAddresses = new String[] {'user@acme.com'}; 
String[] ccAddresses = new String[] {'smith@gmail.com'};

// First, reserve email capacity using size() of query results list
Messaging.SingleEmailMessage mail = new Messaging.SingleEmailMessage(queryresults.size());

// Now create a new single email message object
Messaging.SingleEmailMessage mail = new Messaging.SingleEmailMessage();

// Assign the addresses for the To and CC lists to the mail object.
mail.setToAddresses(toAddresses);
mail.setCcAddresses(ccAddresses);

// Specify the address used when the recipients reply to the email. 
mail.setReplyTo('support@acme.com');

// Specify the name used as the display name.
mail.setSenderDisplayName('Event Organizer');

// Specify the subject line for your email address.
mail.setSubject('New Event Created : '+ Event.Name +' '+ Event.Id);

// Set to True if you want to BCC yourself on the email.
mail.setBccSender(false);

// Optionally append the email signature to the email.
// If true, email address of user executing Apex Code is used.
mail.setUseSignature(false);

// Specify the text content of the email.
mail.setPlainTextBody('You're invited to a new event: ' + Event.Name + ' ' + Event.Id);

// Optionally, you can specify the HTML template you want to use
mail.setTemplateId(value ForId of Event Template);  

// Specify the HTML content of the email.
mail.setHtmlBody('You\'re invited to a new event:<b> ' + Event.Name + ' ' + Event.Id + ' </b><p> 'To view the details <a href=https://(your salesesforce na1 instance or URI /'+event.Id+'>click here.</a>');

// Send the email you have created.
Messaging.sendEmail(new Messaging.SingleEmailMessage[] { mail });