You need to look at the GetLocation method
I dont know about doing this in C# but in VB .Net it would be something along the lines of
Code:
Dim objLoc as mappoint.location
Dim objMap as Mappoint.map
ObjLoc = GetLocation(50.333,-1.222, 100)
objMap.AddPushpin(objLoc)
Getlocation(Lat,Lon,Altitude)
Note this is completely untested but I have done it before and i seem to remember its something along these lines, unfortunatly i'm not near somewhere I could test it at the moment.