You'll need to understand that Painter offers us many ways to create brush variants. Some, but not all, are Captured Dab variants. Others can vary hugely in the way they're created and in the ways they can be used once created.
I strongly suggest that you set aside some time to read and learn more about Painter's brush libraries, brush categories, and brush variants. Then, when you've put what you've learned to use and still have questions (which most people do), at least you'll have some understanding of the correct terminology and more precisely what you need help to accomplish.
1. Use Help menu > Help Topics
2. In the left panel, click the Search tab and type brushes then hit the Enter key. A list of titles will appear in the left panel.
3. Click the first title, the one named Exploring Brush Categories. In the right panel, listed in alphabetical order, are the
Painter 12 brush library's brush categories.
4. Scroll down the right panel to see and read sample brush strokes for each brush category and a brief explanation of
each brush category.
5. Now, in the left panel, click the title named Setting Basic Brush Attributes. In the right panel, read the whole page.
6. Continue clicking titles in the left panel and reading the information displayed in the right panel. Most of the titles should
help you now and others are optional reading.
7. Be sure to read as much as you can about the Brush Control palette's panels, especially the General panel as it contains
the most basic controls for any brush variant. Also take a few minutes to read the titles named:
- Selecting, Managing, and Creating Brushes
- Understanding Brushes
- Brush Management
- Creating Brush Dabs
NOTE: When following the steps to create a brush dab (otherwise known as creating a Captured Dab variant),
Do not hold down the Shift key while dragging the Rectangular Selection tool over the image. This will make Painter
think you want to add to an existing selection and the Capture Dab command will be greyed out. Instead, simply
drag the Rectangular Selection tool over the image to create a square-ish selection around the image.
I have not yet used these steps to create a Captured Dab variant myself so there may be other comments I might
make to help you avoid problems. Until there's time for me to try it, I'll just wish you the best and expect it will probably go well.
8. Unless you're going to be using brush variants from the following
list of brush categories, you won't need to read the information now. However, if you decide later on that you want to use those brush variants or, as with the Impasto category, you plan to use brush variants from other categories that also use Impasto controls, you'll need to learn about Impasto and how to control it and use it. (Impasto, or thick paint, is used in several brush categories other than just the Impasto category.):
Real Wet Oil
Even with what I've suggested in this post, and knowing it's just a start for you, it's still a lot of reading so don't let it overwhelm you. Just take it slowly and with repetition, practice, and time you'll find you've learned a lot.