hey i need a program that i can write pcb layouts and schematics and diagrams. especially pcb i wont to get into board etching. if you know of any manuals on how to sketch boards please tell me. i also need a program to write the pcb layout for the board.
eagle is the de-facto for all you seek, and there is a free (restricted) version availiable on their website
other options include kicad and fritzing
Free options I use, (win32) :
TinyCAD, http://tinycad.sourceforge.net/
FreePCB, http://www.freepcb.com/
This one is limited in available parts but free.
Gives you PCB layout, Schematic and diagram. Even includes breadboard and arduino models. Just like the diagrams used in many guides and examples from the main site.
Fritzing has so much potential; its a shame that more people aren't using it and creating new parts for it - it has a built in part editor, and uses SVG - it can't be that difficult (people make parts for Eagle, so why not Fritzing).
I sincerely hope that Fritzing takes off one day like the Arduino.
Sure it's free, but the lack of part library is the smallest reason I don't use it. Every time I make a design in Eagle, I have to make parts.
No, the reason I don't use it is because the interface is really clunky, unfamiliar, and buggy. And remember this is coming from an Eagle user!
I think they tried too hard to be different. And there are hundreds of basic features missing that are essential to getting decent PCBs made.
If you can afford to spend five to ten times longer to go from a schematic to a PCB, I guess Fritzing is ok to play with. Kind of a puzzle game challenge. But it has light years to go before you can even place Fritzing in the same category as other PCB CAD programs.
I would bet that the Fritzing developers agree, and would not recommend it as a replacement for Eagle or Kicad or other options. They, most of all, probably understand how much more needs to be done.
the reason I don't use [fritzing] is because the interface is really clunky, unfamiliar, and buggy. And remember this is coming from an Eagle user!
I think they tried too hard to be different. And there are hundreds of basic features missing that are essential to getting decent PCBs made.
Ditto. Most PCB cad packages are hard to use in that you feel "oh no, there is SO much more that I have to learn." Fritzing feels more like "oh. That's all there is!?"
[fritzing developers] most of all, probably understand how much more needs to be done.
I wonder if it's even possible to add what needs to be added, and still maintain the simplicity that they want. I had a sort of rude "educational" awakening with some software I had written some decades ago; a serial comm program for PCs. It was quick, elegant, and easy to use, and people suggested I try to sell it. So I fixed it up, added the features necessary to support "anything" as opposed to just the local environment it had been written for, and ... you know, it just wasn't simple or elegant any more 
I wish other apps had something like Fritzing's "breadboard" view, though...
I wish other apps had something like Fritzing's "breadboard" view, though...
That's the one great area where it shines; I haven't seen anything like it before.
I also like the fact that it is open-source; this means that no one individual or company controls it - there aren't any limits, nothing you have to pay for to get more stuff (while I think Eagle is cool and all, its pricing curve is waaaay too steep; there needs to be a middle level in-between the el-cheapo purchased option with only a 2-layer small board, and the "make a larger more layered board, but charge you an arm and a leg to do so" option).
If you need more parts, then make them. If it doesn't work like you expect, then re-code that section (I know, easier said than done - but that is an option; you don't have that option at all with Eagle).
The auto-routing sucks (from what I've played with it); but I have heard the same about Eagle.
I will give Eagle props for have a *nix version, though. For some reason, closed-source app developers have this desire to treat and pretend that *nix is a dead-end backwater, when nothing could be further from the truth. I guess if you don't have at least a 10% market share you aren't worth anything...
Then again, I don't have to deal with virii and trojans on my boxen, so I have that going for me.
I just wanted to chime in on Fritzing, so others won't make the same mistake I did.
I tried using Fritzing to design a board with a 64x64 led array, an 18 pin IC, several resistors, a piezo buzzer, four indicator leds, two switches, and a potentiometer. Not a particularly large or complex project.
It handled it badly. By the time I'd gotten designing my schematic it was taking several seconds for it to respond when I tried to select a component. And the breadboard view was a total mess, with hundreds of wires in a huge rats nest. I suspect trying to render this mess was slowing it down, but disabling all views didn't help.
Another problem was when I tried to clean up this breadboard view, which seemed to have lots of leftover wires connecting to absolutely nothing, things started to speed up, but as I continued tidying up it started to slow down again and got to the point where it was taking more like 30 seconds to respond. I finally saved the file to try reloading it and the file size had soubled, and reloading it didn't correct the issue. So I ended up just leaving it as it was and completing the design with the version I had before I started to try to clean up the breadboard.
I don't know if Eagle is as easy to use as Fritzing, or if it does schematic drawings, but I'll definitely look into using that for my next project because I don't want to go through that hell again.
Fritzing is a nice app if you're making simple circuits with a few components like the examples on the Arduino website, but I would seriously steer clear of it for any real work.