Lodging Capital losses/Gains

Hello, it's that time of the year and this is my first time doing such a thing so excuse my ignorance.

First off, I assume that I am meant to calculate my capital gain/loss from 1st July 2016 - 30th June 2017.
Can this include a mixture of both share investing (ie. Buying shares through Westpac) and CFD/forex trading? Both are of seperate platforms.

Secondly, Where would I lodge my capital losses/gains? I checked ATO website but am unable to find out.

And lastly, if I work casually, how can I use a capital loss to offset tax or get more for tax return?

Thanks for the help.