If you can't see the screen shots, try double clicking on them to make them bigger. :)
1. Control + Alt + N to open a new document
2. Select the "Type" tool, it looks like a capital "T" and choose your font and size of font that you would like. Be sure to type in black, you can click "D" to make sure that black is selected. I have read that it is good to make you image as big as possible. I am just making a watermark, so I am okay with the size that I have selected here. However, you can do anything you like here, you can splatter paint, use text, anything. I am just doing a simple watermark for demonstration purposes.
3. Now choose the "Rectangular Marquee" tool by clicking "m" or clicking on the dotted rectangular box in the tools. Once you have this tool selected, draw a selection around the brush you are trying to create.
4. Once you have selected your image you would like to create a brush out of, go to the "Edit" menu at the top left of your screen, then find "Define Brush Preset"...click it. :)
5. Name your brush, I called mine "Blog Watermark" and then clicked "OK".
6. Go back to the "Edit" Menu at the top left of your screen and find the "Preset Manager", click it.
7. This is how you save the brush you just created as an .abr file in your brush folder. If you do not yet have a brush folder that contains all your .abr files, you should create one. Then within that folder create sub folders for each type of brush that you want to save. For example, the brush I created will go under my "Logo Photography" sub folder in my "Brushes" folder that happens to be located in my "Documents" on my computer.
Now that you are in the "Preset Manager" you need to click on the last image in that dialog box. Now, if you decided to create several brushes, you would need to "control and right click" on each brush that you want in your .abr file. After you have done this click the "Done" button at the top circled in red with the number 2 next to it.
8. Now you just need to save that new .abr file (brush file) into the correct location. For me, that would be in my "documents" in the "brush" folder, under the subfolder of "logo photography". Oh, don't forget to name your brush before you do all of that, I have mine named "logo for blogger".
That is it! So, if you want to use your brush now, you can just click on your brush tool...the paint brush or "b". Then click on the little down arrow, I have it circled in red at the top of the screen. When you click that arrow a little drop menu comes down with all of your brushes. Go to the bottom of the list and click on your brush. Select your color you want to stamp in and stamp away!
9. Later if you need your logo/brush/stamp again. Just go to that same little arrow that is highlighted above when you are in the "brush" tool (1.) then go to the little tinier side arrow (2.) and click it. Then go down to where you see "Load Brushes" (3.) and select that.
10. You will then be brought to where you store your brushes. Just select the brush you want and stamp away! Here is my new brush on a picture I took at Bumpass Hell of Lassen Park in California.