To search using experience groups, select the radio button next to the desired group first.
If your experience group has a smaller result set, you will be taken directly to the search results screen. If the experience group has a larger number of results, you'll be taken to an interim search screen, allowing you to input additional information.
Right is the interim search screen for Political Prisoners. Most of the interim search screens are quite similar, with only a few variations.
Select options here, and you may be taken to a 3rd screen for additional detail.
This is the additional screen for Political Prisoners --> Hiding, Flight, Resistance, Forced (death) Marches. Note the options available here for selection.
Had Concentration Camps been selected on the page above, the options on this page would allow you to search by name, country, or selected camps.