How do you reference fields in a content type?

Hi

I would like to override node.tpl.php but I’m not sure how to reference the individual fields in a content type in D7.
I have a content type to which I added a field field_picture and I want to reference this and the body of the content separately in the .tpl.php. I tried to print render($content[‘body’]); but this outputs both the body (text) in the content and the image I have in the field_picture. So I take it ‘body’ refers to the entire content, but how do you reference just the body field and/or the field_picture field?

Thanks

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