Make edges of a picture tend to transparency

Hello: I would like to make a picture using I think it´s the airbrush but I don´t know which on how to make it blend in with the background or make it tend to transparency (alfa->0) I havn´t got any examples at this moment but if you don´t get what I tend to write I´ll look for an example on the web. Thanks in advance for anyone who helps

Is this what you are trying to do?
http://www.mardala.com/john/test1.jpg

If so, then you'll see that I had an image and I chose a blue background so you could see the result. If the blue background was not there, then the image would go to transparent.

I made an oval selection. Hit Cntrl-Shift-I to select the inverse, then chose Select --> Feather --> (Choose what amount you need.) and hit Delete. If you want it to be a color instead of transparent, just fill the selection instead of delete.

I hope this is what you mean....

Well, kind of. But I´ve been looking for some pictures around the web and didn´t find any, I ´ll keep looking. But let me explain my problem a bit more.

Let´s say I have 4 layers with different opacity.
Layer 1 has 100%
layer 2 has 75 %
layer 3 has 50 %
layer 4 has 20 %

Now My problem here would be that the layers won´t blend in much. I would like from the same picture go to 100% and towards 1 edge to 0% but with a nice blending.
Anyway I´ll keep on looking for some pics similar to want I want.
Thanks marble anyway

Found an example

http://usuarios.lycos.es/spighita/demo.htm

try doing a copy and paste, every time you paste it change the opacity in the layers settings

You could use two methods...
1. Select a Gradient that goes from the solid color to transparent and make a layer filled with that aboce it or...

2. Do the same, except using masks, which will fade out the image rather than filling.

If you need to me to clarify a bit I can run through it step by step.

The other thing, is look real close to what I explained earlier....
They are doing that exact same thing, if you increase the feathering quite a bit you will get the same results.

http://www.teamphotoshop.com/photoshop/tutorials/techniques/vignette/vignette.php

Somthing like this mayby?

Thanks everyone who replied. Can you please give me the steps on doing that with the gradient. I think that´s how I want it solved.

Just select the gradient tool. You can click on the gradient and go into the "Gradient Editor" to choose what kind of gradient you want or to make one.

Choose one that is solid to transparent.

Then if you want you can use the selection tool, maybe add a little feathering to it select --> feather (this is optional - but the example you supplied has what looks like an oval with gradients to either side.)

While it is still selected, make a new layer, now use the gradient tool. You might have to mess with it a bit, or create it on a few layers before you get the right effect. But that is a start....

Marble:
I got everything OK, but I just can´t figure out how to make the gradient effect out to transparency. What color am I suppose to choose so it can recognize it as a picture and not one color. I can make it work with the feather but not the gradient. I´m very greatful for the tremendous patience you´ve had. Thanks again