I'd like to know icons' meaning below the posing box.

I tried to find out information as to them, but I couldn't.

When only the icon of hart-mark has infor. as "(my?) favorite".

Could you tell me what "pencil" and "X" mark mean?

Heart icon: add a post or a thread to your favourites
Pencil icon: edit a post. You can edit a post, provided that nobody has answered, only within a fixed amount of time (not 100% sure, but I reckon it's one week, now)
X icon: delete a post

You might find other useful pieces of information in the FAQs .
Hope this helps. Emotion: smile

Thank you very much for teaching me the meanings of each icon.

I understand them[Y]. Thanks. Emotion: smile