I'm still learning Poser, and one of the problems I have is in making the backgrounds. I've dowmloaded a few things (there was recently a sci-fi backgrounds that had some star trek like rooms etc. But now i've loaded them i'm not sure how to get them into the background in poser 5. I did find where I could load a regular photo for a background, but i'm having problems with the downloaded backgrounds like the sci fi ones--or basically anything I've downloaded.

The best way to make a background is to use the One-Sided-Square primitive prop. Load a square, then place your image on the square. You can move it around, scale it, rotate, change its brightness, etc. You can't do any of that with the basic Background Image.

RunTimeDNA has a free "Infitity Cove" in their DNA FreeStuff. You can load any picture on the 'sky' and another on the 'ground'. It also has the ability of using tilable images and you can turn a morph-swap dial for any many times it'll tile. It also allows for the 'sky' to be angled so you can get different perpective looks out of it. If you want just a sky then make the 'ground' inviable... And then of course there's the store bought sets both at RDNA and DAZ....

I agree with Ockham that the best way to use a background is to apply it to a square. The only problem with that method is that you can sometimes have problems with shadows. (For example your character casting an enormous and unlikely shadow on the Leaning Tower of Pisa.) You can disable shadows in order to solve that problem. Or you can use backgrounds the basic way. The way to load a background is from: File, Import, Import a Background Picture. Dont forget to enable backgrounds when you render. (From your Render Options screen) However, one big disadvantage to loading backgrounds this traditional way is that you will probably have problems with the background becoming pixelated when you render it. Six of one half a dozen of the other. I included a background tutorial with my background sets - Watercolor Backgrounds and Asian Watercolor Backgrounds. If I werent twelve thousand kilometers from home right now, Id offer the tutorial to you for free. :( Hope Ive helped rather than confused you. Best Blessings, --Invidia

Imported backgrounds are rescaled to the size of your current composition window, (often resulting in the pixelation when rendering larger than the composition window that Invidia referred to) which is why everyone is suggesting applying the texture to a prop instead.