There are a few ways to do this.
First, you should be able to do this when configuring your map frame in the Dashboard. Under Layer Actions, scroll down to turn on the "Additional selection tools" and choose your method of selection. For the layer that you want to select and filter from, scroll up and expand that layer which will currently say "Active targets: 0". Expand the filter section, and you should be able to click the Dashboard elements that you want filtered based on this spatial selection.
Another method is to create a selector in the headers section of the dashboard. When you create a selector in the headings section, set the layer to be your regions layer. Then go to the Actions tab and under the Filter drop-down, you can set each indicator to be filtered spatially based on what region is selected in the selector when someone is viewing the Dashboard.
Alternatively, you can filter your indicators based on the current visible map extent under the "Map actions tab". You would turn on the filters in this section the same way above. The only downside of filtering them this way is that your map extent will be bound by the rectangular frame, so if you are trying to filter based on a more abstract shape/area, this option wouldn't work as well vs. one of the other 2 above.
Hope this helps!
