How to improve items? (The Witcher 3: Wild Hunt)

look for rune stones, or whatever they are called, click on the stone and insert

for weapons - runes, such as "Runestone Svarog", "Runestone ...."
for armor - rune glyph quen, etc.

looks like i haven't met them yet.. thanks

Is there any way to combine runes and improve them? well, like, 5 crappy runes in one better,
otherwise + 2% demag from igni ... a little funny)