where is the negative terminal on my 2003 chevy venture?

Your battery has two terminals on it, a positive and negative. The positive will be indicated with a + and the negative with a dash.

Word of warning, do not use your vehicle to jump another, this can cause a voltage spike that will ruin computers. Safest way is to use a jump box and that should be capacitive type.

Told I could ground on any metal engine part.

I know neg should be marked; could not find post.