The Sspunding valve is pretty simple operation and installation. Make sure your oring and cup are fully inserted over the valve.
You will simply fill the cup half full with diluted down sanitizer similar to what you would use in a spray bottle. Twist the valve to the appropriate BAR rating ( this all depends on the processes for spunding).
If you are fermenting under pressure you would close and set after transfer a PSI or bar to your yeasts range (5 to 9 psi .3-.6 bar is common) and run this through the whole fermentation process. Just keep in mind, differences and variants will occur when fermenting under pressure so choose a strand that fits your profile.
To naturally carbonate, I would wait to close up until the last few points of your attenuation point and set it to around the 10 - 13 psi or .7 - .9 bar. The Sspunding valve can be set to a higher pressure than your PRV during the initial few days fermentation so that the discarded krausen comes out through the blowoff tube instead of the Sspunding valve. This will effectively keep the valve shut and clean until fermentation has become less messy.
For safety, always leave the fixed-pressure PRV included with the vessel in place, never exceed the maximum rated working pressure of the vessel at any time during operation.