This shows the file 'birthday' inside directory 'cake'.
The dotted line under "Attributes" shows it has file Properties of 0.
Right click the file, and select 'Change Attributes'.
This is the 'CHMOD' box. You are going to alter the file properties.
The box that pops up has 2 methods of entering the correct number.
Tick the boxes, or enter the required number, and then click OK.
That file has now been CHMOD'ed to 766.
Hidden Files.
In the top menu, click 'Options', then select General Options.
In the box that appears, click the tab named 'Other'.

Click 'List Hidden' then OK.
Now you can see your hidden files.