I use Photoshop 6.0 so this may be different in yours. Modify existing brush - click it in the brush palette, it's icon will appear in the Options bar. lick the Options bar & the Brush Characteristics dialog box appears. Make changes then close. Create a custom brush - Select area of image, choose Layer/New/Via Copy. Choose Edit/Define Brush and Brush Name dialog box appears. Name the brush which brings up the New Brush dialog box, choose spacing and the brush appears on the brush paleete.