haha yea I am regretting not putting slower and thorough tutorial and ramp up on the game! A lot of people are struggling in the beginning!
Once you talk to the person, they give you an 'arrow' rune, which you can equip to the quick bar from the spellbound menu(press x)
Once you have the runes equipped, you can write the rune into the spell sheets on the floor. You can write or erase the rune that's being highlighted with a red square and arrow (which also indicates which rune the sheet is executing)
So for the first puzzle, you will have to write the arrow rune to somewhere before the explosion rune to make the explosion move over by one.
Thanks for playing!