I am new to salesforce. i want to send email with attachment

Here is the method, You can send the document/email with an attachment:

public with sharing class EmailDocumentSend {

public list<ID> documentId {get;set;}

public String email {get;set;}

public list<selectoption> getfindDocument(){

list<selectoption> documentlist = new list<selectoption>();

for(Document docs:[select id, name, type from Document order by name]){

documentlist.add(new SelectOption(docs.id, docs.name+' – '+docs.type));

}

return documentlist;

}

public PageReference emailDocSend() {

list<Document> docmnt= [select id, name, body, contenttype, developername, type from Document where id = :documentId];

for(Document doc:docmnt){

Messaging.EmailFileAttachment attach = new Messaging.EmailFileAttachment();

attach.setContentType(doc.contentType);

attach.setFileName(doc.developerName+'.'+doc.type);

attach.setInline(false);

attach.Body = doc.Body;Messaging.SingleEmailMessage mail = new Messaging.SingleEmailMessage();

mail.setUseSignature(false);

mail.setToAddresses(new String[] { email });

mail.setSubject('Email from Salesforce');

mail.setHtmlBody('Salesforce Doc is: '+doc.name);

mail.setFileAttachments(new Messaging.EmailFileAttachment[] { attach });

Messaging.sendEmail(new Messaging.SingleEmailMessage[] { mail });

ApexPages.addMessage(new ApexPages.Message(ApexPages.Severity.INFO, 'Document '+doc.name+email));

}

return null;

}

}

Visualforce Page

<apex:page controller="EmailDocumentSend" showHeader="false" sidebar="false">

<apex:sectionHeader title="Email Document " subtitle="Email a Document"/>

<apex:form >

<apex:pageMessages />

<apex:pageBlock title="Enter Email Address">

<apex:pageBlockButtons >

<apex:commandButton action="{!emailDocSend}" value="Send Document"/>

</apex:pageBlockButtons><apex:pageBlockSection>

<apex:pageBlockSectionItem >

<apex:outputLabel value="Email to send to" for="email"/>

<apex:inputText value="{!email}" id="email"/>

</apex:pageBlockSectionItem>

<apex:pageBlockSectionItem >

<apex:outputLabel value="Document" for="document"/>

<apex:selectList multiselect="true"  value="{!documentId}" id="document" size="4">

<apex:selectOptions value="{!findDocument}"/>

</apex:selectList>

</apex:pageBlockSectionItem>

</apex:pageBlockSection>

</apex:pageBlock>

</apex:form>

</apex:page>