Start with the curb by making a wooden form that you then fill with concrete. You can make the curb 5 inches tall and 4 inches thick, by cutting two boards that are 5 inches and screwing them to the floor and to the walls. Leave 4 inches of space between them. You can also run steel reinforcing wire along the center of the form. Add roofing paper at the bottom to protect the floor from moisture.
If you're doing the drain plumbing, make sure that the drain pipe ends flush with the floor. This helps ensure that the shower drain remains about 2 inches above the floor. Then, draw a 2.75-inch tall line around the shower pan with a ruler.
When mixing the cement, which should be the kind that is used for brick mortar, make sure that you're getting a dry and nearly crumbly texture. After mixing it, throw it in the space that's about to become your shower. Then, smooth down the concrete, adding more if need be. Shine a light on it in the dark to check if there are any bumps that need further smoothing.
Once the concrete is cured, use Redguard over it, making sure to go up on the walls with it as well. Next, put the top part of the drain in its place. Wait for everything to dry off, and begin tiling. Begin with the floor, which needs to be grouted first. Then follow with the walls the next day.