COT long/short question

can anybody explain me what mean in COT report when
net long position are negative ? or vice versa short net position are negative like

like on picture commercial is -12.372 ? how they can hold negative position ? is it mean they are shot ? but this is net long so i confused.

That means that they are short on it. From your example: commercial traders are on the selling side of the long positions of participants of other types.

Do you know where i can find the Dollar Index on the C.O.T report? I can find other currency but not this? Help is appreciated.

Should be at the bottom of Financials report, the same where currencies are.