Hii

Yes, you are eligible for SSC JE EC Engineering exam after completing Diploma in E&CEngineering. First of all you have to visit the official website of the SSC. There you have to click for new registration. After completion of your registration, you have to apply for the JEC Engineering exam. You must remember to complete your payment after completion of application form. No form will be accepted without payment. 

If you belongs to reserved category then you have zero application fee. 

Hope this helps