Hi,
You can see guidance for listed shares and securities here:
Capital Gains Summary notes
If your shares are listed, then you would include them in the listed shares and securities section of the onine tax return. If they are not listed, then delcare them in the unlisted shares and securities section.
The term "allowable costs" covers the cost of buying and selling the shares. This is the sum of buying the shares plus the fees for buying and selling the shares. This would also include the legal fees.
Thank you.