How to sign a soap request with an encoder, what is DigestValue, SignatureValue, KeyInfo?

Question

SOAP

Good afternoon. The task is to sign the soap request with an ESP.
I can't figure out how the signature principle works. That is, what is DigestValue, SignatureValue, KeyInfo.
As I understand it, I take the key. I parse it. And then something needs to be passed through the encoding. Alas, it took me a week to get to this point (((
There is an example of how it should be

<ds:Signature xmlns:ds="http://www.w3.org/2000/09/xmldsig#">
            <ds:SignedInfo>
                <ds:CanonicalizationMethod Algorithm="http://www.w3.org/TR/2001/REC-xml-c14n-20010315"/>
                <ds:SignatureMethod Algorithm="http://www.w3.org/2001/04/xmldsig-more#gost34310-gost34311"/>
                <ds:Reference URI="#ff268006-c66a-4dea-8fb3-54d819084b9a">
                    <ds:Transforms>
                        <ds:Transform Algorithm="http://www.w3.org/2000/09/xmldsig#enveloped-signature"/>
                        <ds:Transform Algorithm="http://www.w3.org/TR/2001/REC-xml-c14n-20010315#WithComments"/>
                    </ds:Transforms>
                    <ds:DigestMethod Algorithm="http://www.w3.org/2001/04/xmldsig-more#gost34311"/>
                    <ds:DigestValue>DigestValue? </ds:DigestValue>
                </ds:Reference>
            </ds:SignedInfo>
            <ds:SignatureValue>SignatureValue? </ds:SignatureValue>
            <ds:KeyInfo>
                <ds:X509Data>
                    <ds:X509Certificate>код сертификата ? </ds:X509Certificate>
                </ds:X509Data>
            </ds:KeyInfo>
        </ds:Signature>

I would be VERY, VERY, VERY grateful for your help.