The same way you make other Runes, get pure ess and go to the altar ( providing you have the appropriate tiara or talisman ).
The Fire Altar is located near the duel arena in Al-Kharid.
Mostly Fire runes but Law runes and Air runes are not far behind them.
There is no staff like this.
No staff will really MAKE runes; however, some staffs will SAVE you the runes when you use the corresponding spell. Thus, by wielding a staff of fire, or one of the more advanced versions, you will need no fire runes for any spell (for instance, combat spell, or high alchemy) that normally requires them.
Runecrafting the runes is your best bet, or buying the runes from GE, players or Ned in Varrock.
You need level 15 runecrafting Have in your invent Fire runes and talisman or Air runes and talisman and pure essence. If you have fire runes go to the air alter, if you have air runes go to the fire alter then simply use the talisman on the alter. There is only a 50% of success, i recomend wearing a binding necklace to increase this to 100%.
They could be anywhere throughout RuneScape.
read link below
Make runes. Air, Water,...
Check link below
To get runes, you can either buy them from the various magic shops around Runescape, on the Grand Exchange, or make them from rune essence and pure essence at the runecrafting altars hidden around runescape. If you need help, my runescape username is Xeyran.
Fire runes are over-produced on RuneScape, so there are far more on the market than people willing to buy them. However, they will sell if given enough time.
South of the monetary and west of Barbarian village.