Wrapperclass exmple

==========================vfpage==================
<apex:page controller="Checkbox_Class" Tabstyle="Account">
  <apex:form >
   <apex:pageBlock Title="List of Accounts" >
    <apex:pageBlockButtons >
     <apex:commandButton value="Display the selected Records" action="{!GetSelected}" rerender="Selected_PBS"/>
       </apex:pageBlockButtons>
         <apex:pageblockSection >
            <apex:pageBlockSection Title="List of Available Accounts" columns="2" >
                <apex:pageblockTable value="{!accounts}" var="a" >
                    <apex:column headerValue="Select" width="60">
                      <apex:inputCheckbox value="{!a.selected}" id="checkedone" />
                    </apex:column>
                    <apex:column headervalue="Account Name" value="{!a.acc.Name}" width="200"/>
                    <apex:column headervalue="Phone" value="{!a.acc.Phone}" width="300"/>
                </apex:pageblocktable>
            </apex:pageBlockSection>
            <apex:pageBlockSection Title="Selected Accounts" id="Selected_PBS">
                <apex:pageblockTable value="{!SelectedAccounts}" var="s"  >
                      <apex:column headervalue="Account Name" value="{!s.Name}" width="30"/>
                      <apex:column headervalue="Phone" value="{!s.Phone}" width="30"/>
                </apex:pageblockTable>
            </apex:pageBlockSection>
        </apex:pageblockSection>
     </apex:pageBlock>
  </apex:form>
</apex:page>
===================controller======================
public class Checkbox_Class
{
List<accountwrapper1> accountList = new List<accountwrapper1>();
    List<Account> selectedAccounts = new List<Account>();
   
       public List<accountwrapper1> getAccounts()
    {
        for(Account a : [select Id, Name, AccountNumber, Phone from Account limit 20])
        accountList.add(new accountwrapper1(a));
        return accountList;
    }

    public PageReference getSelected()
    {
        selectedAccounts.clear();
        for(accountwrapper1 accwrapper : accountList)
        if(accwrapper.selected == true)
        selectedAccounts.add(accwrapper.acc);
        return null;
    }

    public List<Account> GetSelectedAccounts()
    {
        if(selectedAccounts.size()>0)
        return selectedAccounts;
        else
        return null;
    }  

    public class accountwrapper1
    {
        public Account acc{get; set;}
        public Boolean selected {get; set;}
        public accountwrapper1(Account a)
        {
            acc = a;
            selected = false;
        }
    }
}