in cockpit view of the DGIV, if you press ctrl + down, you will see the downer part of the cockpit
right is a box with crew names on it, you can select the person you want to eva by clicking on the arrows
but before the eva, you need to open airlocks and the nosecone, these buttons by accessed by pressing ctrl + up
if you are on the moon, you cannot have both airlocks open at the same time, because you need to depressurize the sas
just lock the airlocks, then depressurize, then open the outer airlock and the nosecone, and now you are ready for eva in space or elsewhere