I learned the basics by playing @ the interface a bit... then a friend wrote me that Tuturial:
"Open up an image where you wish to isolate something like the above pic where the original was all in focus and I wanted to blur everything but the horses and carriage. Now go: layer<duplicate layer. Oh, and make sure you have what they call the layer palette opened up. Go: Window and then tick "Layers". A box will appear along side your image. I leave this "Layers" palette open all the time. You will notice within the layers box you have two little oblong boxes with two pics of your image. One is called Background. The other is called Background copy. The layer that is live is the one that is coloured (should be dark blue) this means that that is the active layer and you are only changing that and not the original Background or original layer...no damage done if you screw things up LOL.
OK, where were we. Make sure your "Background copy" is selected. If not click on it to make it blue, therefore the active layer. Then go Filter<Blur<Gaussian blur. A box now appears and you can use the slider to taste. If you are replicating a shallow depth of field just set the radias slider control anywhere between say 4 and 9 and click ok. Now at the bottom of the layers palette is a box with what appears to be a circle in it. Hold the curser over it and it should say "Add layer mask" Click on it and you will notice back up in your "Background copy" layer a white oblong box has appeared. This is your mask. Read up on masks when you have 10 minutes they are neat and you will use them all the time in the future. Now in the long thin palette than runs vertical (down near the bottom of the palette you have two boxes. One says "Set foreground colour" and the other says "Set background colour" the top one should be black and the bottom one should be white. If not hit the toggle between the letters X and D till they are. Now grab a paint brush in the same vertical palette marked "Brush tool" At the top of your screen you will now have a horizontal palette or tool bar. Make sure you go into "Brush" and pick a "Soft round brush" You will also see an "Opacity" slider up the top as well. Set this to 100% for this instance. You will change this as you become familiar with it for various effects, but for the time being try 100%. Now make sure you left click your mouse on the mask layer (the white one) within the layers palette. This is to make sure you are working on the mask only. Then with the paint brush start painting in the area you wish to come back sharp. To change the size of your brush just toggle between these " [ " and " ] " keys. The one on the left is to make the brush smaller and the one on the right to make it larger.
Now painting with black takes you back. If you stuff up use the "X" or "D" key to make white the top or foreground colour and paint over the mistake. This takes you back the other way. Hope this gets you on the right path. Enjoy."
With help of this guide I learned how to use layers and masks, which are some of the most important stuff @ Photoshop... then I was able to do stuff like that:
Using photoshop - where to start?
