I want to insert contact to salesforce, I'm using developer.force account. How can I insert contact? I can't use upsert() method because I"m unable to specify External Id field. Can I create External Id field for connected application using developer account?

I'm facing the following error:

"The REST API is not enabled for this Organization.","errorCode":"API_DISABLED_FOR_ORG"

How to fix this issue? Or how to enable REST API for organisation?

Currently I'm using 30 days trial version of salesforce.com.

I'm facing the following error:

"The REST API is not enabled for this Organization.","errorCode":"API_DISABLED_FOR_ORG"

How to fix this issue? Or how to enable REST API for organisation?

Currently I'm using 30 days trial version of salesforce.com.