How to open a pole lamp

I need to replace the lightbulb in my outdoor pole lamp. The cover looks like it has a tab (left side in photo), but I guess I don't have the hand strength to pull it out enough and in this cold weather, I might crack that cheap polystyrene plastic if I try to force it. Any suggestions?

lampA.jpg
 

There appears to be something printed inside of the top. Can you read that, does it have the manufacturer and product? If so, you might be ables to google it and find an owners manual with instructions.
 
Mine looks similar, and on the top, there are four little decorative knobs, which unscrew and the top comes off, can then reach down and change bulb?
 

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