Minimums can be set in DH or BARO (MDA - minimum descent altitude).
DH is the height above ground where you must make a go around if you do not see the runway and/or approach lights.
MDA is the minimum altitude you can descend to when flying a non-precision approach (NDB, VOR etc) or a cricling approach. You can stay at that altitude after descending untill you are at a missed approach point, usually a VOR, or DME from a VOR or NDB or even time from the final approach fix.
Here the more expanded explanation from wikipedia: Decision heightA decision height (DH) or decision altitude (DA) is a specified lowest height or altitude in the approach descent at which, if the required visual reference to continue the approach (such as the runway markings or runway environment) is not visible to the pilot, the pilot must initiate a missed approach. The specific values for DH and/or DA at a given airport are established with intention to allow a pilot sufficient time to safely re-configure an aircraft to climb and execute the missed approach procedures while avoiding terrain and obstacles.
Minimum descent altitude (MDA)The minimum descent altitude (MDA) is the lowest altitude (relative to MSL) to which descent is authorized on final approach, or during circle-to-land maneuvering in execution of a non-precision approach.[4] Unlike with DH or DA, a missed approach need not be initiated immediately upon reaching the altitude. A pilot flying a non-precision approach may descend to the MDA and maintain it until reaching the missed approach point (MAP), then initiate a missed approach if the required visual reference was not obtained. An aircraft must not descend below the MDA until visual reference is obtained, which differs slightly from a DH/DA in that while the missed approach procedure must be initiated at or prior to the DH/DA, because of its vertical momentum, during a precision approach an aircraft may end up descending slightly below the DH/DA during the course of the missed approach.
If a runway has both precision and non-precision approaches defined, the MDA of the non-precision approach is almost always greater than the DH/DA of the precision approach, because of the lack of vertical guidance on the non-precision approach: the actual difference depends on the accuracy of the navaid upon which the approach is based, with ADF approaches and SRAs tending to have the highest MDAs.
Also see an example of the differences in DH and MDA on an approach plate.
You can see (in left bottom) that the decision altitude (DA) for the ILS approach is 228 feet above mean sealevel. The decision height is the number behind that (200') so 200 feet in this case. That's what you set in the green 'radio' numbers.
One square to the right you see the minimums for an LOC (localizer approach) this means when the glideslope of the ILS is broken or in maintanence, hence the (GS out). The minimums of the LOC approach are an MDA of 360 feet above mean sealevel or 332 feet above the ground. In this case you set the green 'baro' to 360.
Both minimums are ment for a manual landing so no Autoland. (you can practise autoland of course but that's for training and mostly currency reasons). That's why the minimums of this page are called CAT I minimums. And every IFR equipped aircraft can fly this approach.
Again different story for CAT II and CAT III a, b, © approaches.
Hope this clears a few things up.