I'll bite.
The beauty of sfc is that no 'programming' experience or knowledge is required; you just need to now the sequence. So, for a washing machine, STEP 1 may be 'wait until door shut', and the TRANSITION is 'door shut switch'; then maybe the next STEP is 'fill drum with water' and the TRANSITION would be drum full. I've put the IEC terminology (STEP, TRANSITION) in caps.
Decalre your sequence, and the ins and outs just write themselves IME.
Out of interst, in your OP, why mention ladder?
Oh; never used GX-Developer, but daresay it obeys the IEC rules. If it doesn't, use something else. My £0.02
Pp