I would just add a few things to what Starwoo said:
The "slow-drying" ink she mentioned can be purchased as special pens, or brushes, or as stamp pads.
But other inks and materials are slow-drying too (so they're also sticky for awhile) ...like the ink from ballpoint pens, and glycerin (buy at the drugstore and apply with a toothpick or brush, or saturate a pad for stamping), and pre-colored pigment-based ink pads I believe. So you can draw freehand with the inks/glycerin, or use ordinary stamps on a stamp pad with one of those materials, to create the designs.
The special "embossing powder" actually melts when the heat is applied later, and eventually forms a continuous pool (which will be slightly raised when it's cool and hard).
Be aware that other fine glitter or "powders" won't work, though they often come in similar little bottles, etc.... you'll need to use "embossing powders." They come in all kinds of colors, as well as metallic or pearlized versions, etc, and they can be mixed together to create new colors or effects.
The color of the ink or paper won't matter because the embossing powders are all opaque I think so they'll hide any colors underneath.
You can create the heat in several ways:
... The cheap way is to swish the inked and powdered paper slowly across the surface of a hot iron, or sway it just above a light bulb (paper doesn't burn till it's 450 degrees F, but you could get that hot if you don't keep it moving). If you're using a thicker paper like cardstock, it would take longer for the heat to get through to the powder.
...The other way is to use *blown* heat from some kind of heat gun (the type that's purchased in a craft store is called an embossing gun, while the one purchased in a hardware store is usually just callled a heat gun and gets a whole lot hotter than an embossing heat gun --though in a pinch you could hold it farther away or use underneath the paper, I guess).
This is great fun to do for little gift tags and things too (I like to use colored papers as well), and stationery, cards, announcements, or just anything.
You can also color in the empty areas, or do other colors and/or designs (always one color at a time), or cut them out and use elsewhere, etc.
Btw, this type of "embossing" is different from the *impressed* kind, often called "dry embossing." In that case, a small ball-headed tool is pressed and dragged over a the back of a piece of paper, etc., which is sitting on a soft-ish base... that allows the embossing tool to make an indention wherever it draws, so that the whole area inside any indented lines will appear raised when viewed from the front side of the paper.
HTH,
Diane B.