Before starting to paint with BPainter, your scene needs some small preparation, so you experience a smooth painting experience.
01 Enter Texture Paint Mode
To start painting you need to make sure to enter the Texture Paint Mode. Select the object you want to paint on and then enter the Texture Paint Mode. Once this is done, a new tab appears in the side bar. Select the BPainter tab and you are almost good to go.
02 Enable the right Viewport Shading
One important function you need to enable to properly display all layer textures correctly. Blender has different shading modes. To display layers correctly you need to make sure enable Material Viewport Shading. This mode is needed.
03 Setup a UV Layout
Setting up a uv layout is super easy in BPainter. If you haven't created a custom UV Layout yet, BPainter will create automatically one by creating a new Paint Layer. It is still recommended to create a custom UV Layout, since you have much more control auf how your UV Layout will look like. For automatic UV generation BPainter uses a Blender internal function. This works nice for quick testing, but it won't offer the best layout that is possible.
04 Start Painting
Once youe make sure the 3 steps above are properly done you are good to go. Just select your favorite brush and start painting on your model.