Make a backup of the original demo templates
cp -rv /var/lib/ledgersmb/templates/demo /var/lib/ledgersmb/templates/template1 # on Ubuntu this was sudo cp -rv /etc/ledgersmb/templates/demo /etc/ledgersmb/templates/template1
Go into the LedgerSMB admin control panel and change the template from demo to whatever you named the new directory.
cd /var/lib/ledgersmb/templates/template1 # on ubuntu it's in /etc/ledgersmb/templates # backup your original files just in case cp logo.png logo.png.orig cp logo.eps logo.eps.orig
edit your new logo.png in Gimp to be something that you want e.g.
Save as logo.png
Also save as logo.eps
# copy new logo's into your custom templates directory cp logo.png logo.eps /etc/ledgersmb/templates/template1/