Howto use DLL's?

I'm not sure if this is the correct way to start, but this is what I made so far :

dll = LoadlibraryA ("qlib32")

Global QAPIExtOpenCard:Long(cardid:Long, devnum:Long) = GetProcAddress(dll, "QAPIExtOpenCard")
Global QAPIExtWriteDo32:Long(cardhandle:Long, channel:Long, value:Long, mode:Long) = GetProcAddress(dll, "QAPIExtWriteDo32Card")
Global QAPIExtCloseCard:Long(cardhandle:Long) = GetProcAddress(dll, "QAPIExtCloseCard")

If this is correct I can go one step further...