You're not getting the best info here, so I'll have a quick go at helping. I will preface my remarks by saying that this is general info and not tailored to you. Your circumstance seems such that you have current year gains of 10k and current year losses of 5k. If the figures are wrong the principles are the same. To get the first bit out of the way you must apply current year losses to current year gains to get net gain for the year. In this case your net gain seems to be 5k.
There is no such things as capital gains tax. The net capital gain you make in any year is just part of your taxable income like wages, interest etc, and will be assessed for income tax. If, as you say, you have no other income then your taxable income should be 5k and you utilise the tax free threshold and no tax is payable.
There is no option to carry fwd a loss if there are gains to offset against in the current year. Remember this is capital losses not tax losses.
I say to everyone that the ATO website is brilliant for these queries, and really quite easy to navigate. Half an hour of reading could save many tax agent fees, but it's your decision.
