Hi there.
I'm not sure if I understand your question.
What do you mean by creating a brush? Are we talking CorelDraw environment?
Do you mean creating a pattern fill? If so, follow the instructions:
1. Create an area (rectangular, square, whatsoever).
2. Go to the dropdown fill tool (by clicking the lowerright triangle) and choose the 3rd option (Pattern Fill Dialog)
3. Choose Bitmap checkbox (from 2-color, Full Color and Bitmap checkboxes in the upperleft corner).
4. Click the Load button and find your jpg file.
5. Set the different values (Origin, Transform, Size, Row or column offset, etc.) according to your needs.
Make several experiences to meet the desired look.
Makiavel