Can I whiten my real teeth at home even though I've a bridge & porcelain screw-ins on top left side?

Yes you can whiten natural teeth...but not fillings  or porcelain crowns.  So be aware that the shade of your crowns are what they are and by whitening natural teeth you may make them more noticeable and less white than the ones you whitened.  Speak to your dentist if you are unhappy with the shade of porcelain restorations.  He/she may have a solution.

All whitening products today whether over the counter or from a dental professional can only whiten tooth structure specifically enamel. They will not have any effect on fillings or porcelain. 

You can whiten your teeth but remember that your veneers and bridge will NOT change color with whitening.  So if your veneers match the color of your natural teeth now they will likely look less white compared to your natural teeth after whitening.