What are the exact quality standards?

Can anyone tell me exactly what are the quality standards for the insertion of works
, they do not write specifically what are the dimensions for making the work?
I do not understand if only the pevious image should be 590x590 pixel or all the work?
Who can and will do a little to make me aware it would be grateful to him

hi indeed, u have to stick to 590 in terms of width, for the height, i think the limit is around 7 or 8000 …

Thanks, I thought that both the width and the height must be the same

no, no need, just fixed width