I have seen numerous requests on other blogs about sample code to on how to update entities in CRM. One way is to use the CRM web service to update business entities, however by doing so, you're only limited to out-of-the-box entities with system attributes. To retrieve anything more "dynamic," you'll have to employ other methods. Please remember that in order to update any record, you must have the proper permissions on that entity.
Below is a code example of how to update a record:
public void UpdateEntity(ICrmService service)
{
//variable initialization
DynamicEntity entity = new DynamicEntity(); //target entity to update
TargetUpdateDynamic targetUpdate = new TargetUpdateDynamic(); //used to update entity
UpdateRequest updateRequest = new UpdateRequest(); //request to update entity
entity.Name = <entity name>
//add the properties you want to update on the entity
entity.Properties.Add(<property1>);
entity.Properties.Add(<property2>);
entity.Properties.Add(<property3>);
//set the target to update, and the request to update for
targetUpdate.Entity = entity;
updateRequest.Target = targetUpdate;
//execute the update request
service.Execute(updateRequest);
}