<apex:page controller="AccountBudget">
  <apex:sectionHeader title="Account Budgeting" subtitle="Page1"/>
    <apex:form >
      <apex:pageBlock title="Account Selection" mode="edit" id="thePageBlock">
        <apex:pageBlockButtons >
          <apex:commandButton action="{!FromOne}" value="Next"/>
         </apex:pageBlockButtons>
   		 <apex:pageBlockSection columns="3">

           <apex:pageblockSectionItem >
	         <apex:outputLabel value="Sales Centre:" for="SalesCentre"/>
	         <apex:selectList value="{!SalesCentre}" size="1" id="SalesCentre">
	           <apex:selectOptions value="{!SalesCentres}"/>
	             <apex:actionSupport event="onchange" rerender="Accounts"/>
	         </apex:selectList>
	       </apex:pageblockSectionItem>

	       <apex:pageblockSectionItem >
	         <apex:outputLabel value="Item Class:" for="ItemClass"/>
	         <apex:selectList value="{!ItemClass}" size="1" id="ItemClasses" >
	           <apex:selectOptions value="{!ItemClasses}"/>
	           <apex:actionSupport event="onchange" rerender="ItemClassDescriptions"/>
	         </apex:selectList>
	       </apex:pageblockSectionItem>

	       <apex:pageBlockSectionItem >
	         <apex:outputLabel value="Year"/>
	         <apex:selectList value="{!Year}" size="1">
	           <apex:selectOptions value="{!Years}"/>
	         </apex:selectList>
	       </apex:pageBlockSectionItem>

	       <apex:pageblockSectionItem >
	         <apex:outputLabel value="Account:" for="Accounts"/>
	         <apex:selectList value="{!Account}" size="1" id="Accounts" disabled="{!ISNULL(SalesCentre)}">
	           <apex:selectOptions value="{!Accounts}"/>
	           <apex:actionSupport event="onchange" rerender="ItemClasses"/>
	         </apex:selectList>
	       </apex:pageblockSectionItem>

	       <apex:pageblockSectionItem >
	         <apex:outputLabel value="Item Class Description:" for="ItemClassDescription"/>
	         <apex:selectList value="{!ItemClassDescription}" size="1" id="ItemClassDescriptions">
	           <apex:selectOptions value="{!ItemClassDescriptions}"/>
	         </apex:selectList>
	       </apex:pageblockSectionItem>

      	 </apex:pageBlockSection>
  	 </apex:pageBlock>
  </apex:form>
</apex:page>