I suggest to move bibisco
folder to $HOME/.local/share
Download this icon and save it in the folder where the bibisco executable file is.
Then make a file with this content:
[Desktop Entry]
Name=Bibisco
Comment=Novel writing software
Exec=/home/<username>/.local/share/bibisco/bibisco
Icon=/home/<username>/.local/share/bibisco/bibisco-circle-hr.png
Terminal=false
Type=Application
Categories=Office;
Here <username>
should be replaced with your username.
save it as bibisco.desktop
.
Then move bibisco.desktop
to $HOME/.local/share/applications
If you want to run it from terminal then there some are other steps.