i updated the user as a Service cloud user in user settings. But, where can i see Service Cloud Console in my free developer edition?
There is an example application for the service console included in the developer edition, but it isn't enabled for any profiles in my recent dev orgs.
Navigate to Setup -> Create -> Apps and you will see Sample Console in the apps list.
Click the edit link next to this and scroll to the bottom of the page and you will see the profile availability - on mine its empty:
Check the boxes for the profiles that you want to have access and click the 'Save' button. The sample console application will then appear in the applications menu at the top right.
You can also create your own custom service console applications if you don't like the sample one - simply select the console radio button after you click the New button.