i have custom object A.B AND C Object have Lookup relationship with A OBJECT.In A object Have custom field name: delevery template (its a rich text).it is work as a EMAILTEMPLATE.... My task is whenever create a new record under A Object -when select 'B'&'c' custom field...custom field name: delevery template (its a rich text) section automatically send email to 'B' object emailfield. here i am use delevery template (its a rich text) section like a plaintext for email..how to automatically send email whenever create a new record under A Object -when select 'B'&'c' custom field Using apex trigger.. please give your knowledge.
The example at the bottom of the apex guide on outbound email is very similar to what you want. This apex code will fit into a trigger.
http://www.salesforce.com/us/developer/docs/apexcode/index_Left.htm#StartTopic=Content/apex_forcecom_email_outbound.htm