How to desaturate the background without desaturating the characters in the image?

[spark swift]

Please help, I really need to know how to do that?

[hybrid prairie]

Use a Hue/Saturation Adjustment Layer with a Layer Mask. Mask out the characters. Turn the Saturation down to 0.

[spark swift]

How do I mask out a character?

[wheat mesa]

Counter question:
Are your characters and your background on different layers?
Can you please show a complete screenshot with the layers panel visible?

[spark swift]

Actually, I rendered the artwork in gmod, and now I want to desaturate the background without desaturating the characters

[wheat mesa]

That doesn't answer my question, but I assume now that everything is on one layer. And then masking is mandatory, as D.Humann has already written. Please have a look at a few basic tutorials on masking in Photoshop first. Then if you have any questions - just get back to us.

[hybrid prairie]

Is this, more or less, the result you're after?

[spark swift]

Yeah

[hybrid prairie]

You'll have to make a selection. Then use the selection to make the mask. You can always refine the mask afterwards. This might help get you started...