Using jQuery and REST Endpoints is one of the easiest way to get record details in CRM 2011.
To do this you just need to include:
1. jquery-1.6.2.min.js (or just get the latest version)
The SDK provides some functions for retrieving records:
Use retrieveRecord if you know the ID of the record. Otherwise, use retrieveMultiple if you want to get the record(s) based on some filters as it will return an array of result objects.
In a custom entity form, I have an Account lookup field and an Account Number field. I want to auto-populate one of the field based on the other field and vice versa. Therefore:
Hope this helps,