Hi!
Im trying to create an LCD monitor or at least something like that. I wanted to create it’s leds but I could not create a material that let the light go through.
How can I create an object that seems to be lighting?
vargadanis,
In materials…shaders tab…bottom right, there is an “Emit” slider. Try that.
Best of Luck!!
No, don’t do that. 
Emit will actually emit, but it’s not going to give you the effect you want. Well, I don’t know for sure what effect you’re going for, but Emit is more useful as a fill light situation than a source of illumination for a thing.
Now, as with lights. For an LCD monitor usually you position a rectangular area light, and map a “screenshot” image as a lighting texture, but reversed, and it looks like it’s shining out, illuminating the nearby area like the keyboard and desk, etc.
BTW, LCD monitors and LEDS? Huh? 
You mean like the power on indicator, I take it? Stick a lamp inside it with a really really short falloff, and make the LED a glass or really translucent box.
Pictures being worth… whatever they’re worth. Note there are 3 shadows from the cup, the scene light above, but also each monitor… I made the table more reflective than is normal to clearly show the light casting of the texture (called projector in any other 3D program, but hey this is Blender!)
Wov…
I got it… I have alredy done several case study with emit function and I like it. But area lights… I havent heared about them till now… I will check what are they good for… Thanx for your advice.
One more thing… have you added the screenshots after you had created the 3D objects with a photo editing program or during the creation?
No, I’m sorry, I guess I didn’t explain well.
The screenshots are used twice. Once as a texture map on the faces of the “monitor”, and those are set to emit about 0.3 I think, just enough to make them look like backlit LCDs… emit makes things glow brighter, like they are giving off light, but they do not light up a scene as a real light source does. (nor can you adjust them other than the Emit slider.)
But you use the same screenshot again, on the area light, as a texture. The area light then projects the image outward, like, well, like a projector. Or a real monitor. This scene is over-exaggerated to make a point on how it’s done, but I guess I should have worded it better.
Does this make sense?
edit: also, BTW, never follow any of my tips if you’re a low-poly Game Engine user/modeller. I don’t do that. I frequently have scenes go over 1 hour per frame at render, on a fast dual core machine, and eat up a gig or two of RAM rendering a couple million polygons. I have zero use for the GE at this point. Blender is many things to many people.
Could you explain more how to do the monitor lighting part?