Not much different to DE shaving really.
The smaller the angle between the blade and your skin the smoother and less scraping will be the result, so keep the top cap almost level with your skin then move the handle down until you feel the magic. As always, no pressure needed.
The first use of an SE blade can sometimes feel aggressive so take it easy on your first use and don't judge the razor on its first use of the blade.
I would advise taking out the blade after each shave and cleaning the razor gently and wiping the blade, then air to dry separately. This is not just because "I'm OCD" but because yours is a family heirloom and you don't want anything bad happening to it rust-wise.
No more difficult than DE shaving. It looks in great shape, so count yourself lucky to be able to give it a whiz and the most important thing - enjoy using it.