If you want an informed reference on what Manning did wrong according to the UCMJ - here it is. There are a number of UCMJ articles that are brought against him, and may be more or less come trial time (the article explains this).
But you have to know, the military doesn't just hand you a classification and send you off to work with classified material. There is training involved and testing to ensure you know just what your responsibilities are, and the possible consequences if you screw the pooch.
Doesn't matter if Manning sold or gave the info away. Doesn't really matter, for most of the charges, what the actual contents of that classified info are. What matters is that he shared protected classified material with non-classified folks. That right there is a serious charge.