The point of this noise generator is not to give you a plain background noise. It allows you to regulate auditory cognitive load with ease to adjust to your current task, so that you can keep focus when you feel bored or distracted.
Left side is your typical noise generator. Use existing sounds, add new ones, mute them, change volumes, the usual stuff. On the right side however, you have topical groups of sound sets. You can quickly move within the group to adjust intensity of noise.
Pick a topic from the right side by clicking < or > buttons. Generally intensity of sets goes: Nature > Industrial > Human, with Noise and BPM Forest being their own things, but pick something that doesn't annoy you more than you want first and foremost.
Once you have a topic, you can adjust the intensity of the noise with Lower and Raise buttons, as well as with Forward >>| and |<< Backward buttons. If those buttons don't work for you for whatever reason, you can download local open source version from: Stimulant Noise on GitHub, because by switching back to the page all the time you'll miss the whole point. Unless you have multiple monitors, I guess.
Once you picked a topic, set the intensity (probably to high) and start doing whatever you planned on doing. If you feel too distracted, you can lower the intensity of the noise with |<< Backward button. If you feel like you're not getting enough noise, you can raise the intensity back with Forward >>| button.
Dynamically adjusting auditory cognitive load allows you to keep focus on your task, while not being distracted by the noise. Basically it lets you stay on top of this curve:
If you want to know more, I wrote about it here:
Why Is Nobody Serious About Managing ADHD With Sound?