Amazon MWS Signals Pricing

I watched the documentation scratching my head, wondering how to submit an XML feed that would do something as easy as changing the price of an inventory item.

I watched an example of the XML feed they give, as shown on page 15 in this link , as this is the only example I found that I don’t know how to go about inserting or editing products in the seller’s inventory. can someone give me some advice

given example

POST /?Marketplace=ATVExampleDER
  & Action=SubmitFeed
  &Merchant=A1XExample5E6
  &FeedType=_POST_PRODUCT_DATA_
  &AWSAccessKeyId=0PB842ExampleN4ZTR2
  &Version=2009-01-01
  &Signature=SvSExamplefZpSignaturex2cs%3D
  &SignatureVersion=2
  &SignatureMethod=HmacSHA256
  &Timestamp=2009-01-26T23%3A51%3A31.315Z HTTP/1.1
Content-Type: text/xml; charset=iso-8859-1
Content-MD5: ExampleMd5HashOfHttpBodyAsPerRfc2616Example
User-Agent: MWSTestsuite/2009-03-05 (Language=Java/1.6.0_11/50.0/
Sun Microsystems Inc.; Platform=Linux/i386/2.4.21-50a6smp;
MWSClientVersion=2009-03-09)
Host: mws.amazonservices.com
Transfer-Encoding: chunked 

Feedcontent

<?xml version="1.0" encoding="iso-8859-1"?>
<AmazonEnvelope xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:noNamespaceSchemaLocation="amzn-envelope.xsd">
    <Header>
        <DocumentVersion>1.01</DocumentVersion>
        <MerchantIdentifier>M_EXAMPLE_123456</MerchantIdentifier>
    </Header>
  <MessageType>Product</MessageType>
  <PurgeAndReplace>false</PurgeAndReplace>
  <Message>
    <MessageID>1</MessageID>
    <OperationType>Update</OperationType>
    <Product>
        <SKU>56789</SKU>
        <StandardProductID>
          <Type>ASIN</Type>
          <Value>B0EXAMPLEG</Value>
        </StandardProductID>
        <ProductTaxCode>A_GEN_NOTAX</ProductTaxCode>
        <DescriptionData>
          <Title>Example Product Title</Title>
          <Brand>Example Product Brand</Brand>
          <Description>This is an example product description.</Description>
          <BulletPoint>Example Bullet Point 1</BulletPoint>
          <BulletPoint>Example Bullet Point 2</BulletPoint>
          <MSRP currency="USD">25.19</MSRP>
          <Manufacturer>Example Product Manufacturer</Manufacturer>
          <ItemType>example-item-type</ItemType>
        </DescriptionData>
        <ProductData>
          <Health>
           <ProductType>
              <HealthMisc>
                <Ingredients>Example Ingredients</Ingredients>
                <Directions>Example Directions</Directions>
              </HealthMisc>
            </ProductType>
          </Health>
        </ProductData>
    </Product>
  </Message>
</AmazonEnvelope>