How to save changes of retrieved records in a retrieveMultiple web service

Hi,

In Opportunity, I have a Javascript that retrieves some related records. After a couple of validations some fields of the retrieved records change and I have to Update them but I don't know how, I mean, after the retrieveMultiple call, I have an array with all the related records and with loop I change them, but the changes doesn't got save, if I go to the record in the CRM, the data still the same that was before.

I'm searching for something like this:

Xrm.Page.data.entity.save(RetrievedRecord);

Thanks in advance!

Regards.