There isn't a way given, really. It's been implied countless times, however, that extremely powerful or talented witches and wizards can create magic/magical items; Dumbledore created the Deluminator, the Peverell brothers created the Deathly Hallows (or so it is hinted - as it's unlikely for Death to really have given the items to the three brothers, the most plausible explanation is that they made them themselves), Snape created a few spells, etc.
Sectumsempra
Yeah! George Weasley loses a ear cause Severus Snape Cursed it of.
Severus Snape casts 'Sectumsempra' at a deatheaters wand hand, but misses and hits George's ear.
Tobias Snape is Severus Snape's father.
Snape uses Sectumsempra to cut off a Death Eater's wand arm but misses and hits George's ear.
Yes, it was invented by Severus Snape.
Sectumsempra
that spell is 'sectumsempra'
Cursus are found for an instance in Harry Potter Severus Snape inventesd the Sectumsempra curse
Vulnera Sanetur was the song-like incant of a healing spell and counter-curse to Sectumsempra spell, both of which were invented by proffered Severus Snape.
The three spells that Severus Snape invented, that we know of, are the nonverbal Levicorpus, which hangs your opponent upside-down in midair by the ankle, the counterjinx of Levicorpus which is Liberacorpus, and Sectumsempra, which gives the equivalent of slashing your opponent with an invisible blade or sword.
Severus. I know a song Snape Snape Severus Snape! Found it online
Yeah! George Weasley loses a ear cause Severus Snape Cursed it of.
In the book, Snape uses a non-verbal spell, so we don't know which spell he used, In the movie, the spell Snape uses is "Vipera Evanasca".
I'll name one; people can discuss if they want: Sectumsempra; invented by, non-the-less, Severus Snape.
Severus Snape casts 'Sectumsempra' at a deatheaters wand hand, but misses and hits George's ear.
No, Severus Snape died and never married.