@using Umbraco.Cms.Core.Services
@using Umbraco.Cms.Core;
@inject IContentService ContentService
@{
// Create a variable for the GUID of the page you want to update
var guid = Guid.Parse("32e60db4-1283-4caa-9645-f2153f9888ef");
// Get the page using the GUID you've defined
var content = ContentService.GetById(guid); // ID of your page
// Create a variable for the GUID of the member ID
var authorId = Guid.Parse("ed944097281e4492bcdf783355219450");
// Create a udi
var memberUdi = Udi.Create(Constants.UdiEntityType.Member, authorId);
// Set the value of the property with alias 'author'.
content.SetValue("author", memberUdi);
// Save the change
ContentService.Save(content);
}