Glowstone Dust is obtained by destroying Glowstone Blocks, which are only found naturally in the Nether. It can be mined by hand, though it is mined quickest with a sword (however using a sword will deduct two uses from it). Glowstone Dust can also be obtained by putting a Glowstone Block into a Macerator, which will yield 4 Glowstone Dust. This is a better way to obtain Glowstone Dust as opposed to simply breaking a Glowstone Block, as breaking a Glowstone Block by hand does not guarantee the return of 4 Glowstone Dust.
You may use different Dyes to make Lumar.