Mixing concrete is actually very simple. There are a few pointers that can help, however.
You can buy pre-mixed cement and follow the instruction on the package, or you can mix up your own. For special applications and larger areas it is best to mix your own. Cement or mortar is not hard to mix and pour, but plan on expending a lot of physical effort on the job. It is a labor-intensive job. Consider wearing a mask to keep from breathing irritating dust and gloves to keep lime products off your skin.
Add lime if you want your cement to have a stronger adhesion. Lime is an irritant. In fact, the Portland cement is not good to breathe either, so -- again -- keep hands covered especially when using the dry materials. And do all mixing outdoors or in a well ventilated area. You can also add color to the mixture if you want to tint the cement you will be using. Colors come in powdered form and can be mixed in with the other ingredients to the intensity you want.
When the job is poured, you can create a surface texture by using stamps, brooms or anything else that will form an impression. Or you can rub in powdered pigments for shaded colors or press stones or other interesting materials into the surface.