effects tab not activated & removal of background 'hissing'

I have just downloaded Audacity 2.0.0 (Unicode). I cannot activate any of the actions on the effects tab, even when I have highlighted the part. Could anyone help?
I would like to remove background ‘hissing’ but do not have part of the recording with this noise only to use as example, as the whole audio is spoken word with low background music throughout. Is there a solution to this? Thanks

Ensure that Audacity is “stopped” (not playing, not recording and not paused).

The Noise Removal effect requires a noise sample to create a “Noise Profile”. The Noise Profile then tells the Noise Removal effect what sort of sound to remove.
You may be able to “fake” a noise sample by using “Generate > Noise” and then filter the noise (with the Equalization effect) and adjust the loudness (with the Amplify effect) to create some noise that is similar to the background hiss that you want to remove. Create this noise on a separate track so that you can delete that track after you have removed the noise from the voice/music track.
The more similar the noise that you generate, the better the Noise Removal effect will work, but note that even with a perfect noise sample the Noise Removal effect can only really cope with low level noise.

Hi Thankyou for your quick reply. I have managed to remove the background 'hissing, but it has distorted the background music and the spoken word voice. i have tried reducing the noise 24 and lower. Can you suggest anything. I am not sure what the other tabs do i.e. sensitivity freq. smoothing. thanks Val