Ran08 wrote:Thank you for your opinions everyone!

At least... now I'm sure it's better to go bigger. ^^
Haha, and you're right
tempus, I think I belong to the first group. XD I don't know how to save images properly. Although, in my case, I don't know how to make png files into jpeg. Something new to learn~
And by the way, the background does have a nice quality. I can't believe the file size is so small. Must. Learn. How.
I'm sure you'll find a way

If you don't have Photoshop, there'll probably be file converters out there. GIMP is a free alternative to Photoshop. The thing is to make sure the exporter gives you options, especially for compression. In Photoshop it's a little 0 - 12 slider with 8-10 being the ideal setting. I imagine it's similar in other good image editors. Don't save JPEGs (or anything for that matter) in MS Paint... I... just don't
The most important things to learn about are lossless file formats vs lossy ones, compression, and what each file format's strength is. There's other stuff, but it's not as big of a deal as those things. JPEG vs PNG is quite interesting really;
this image is a 1280 x 1114 PNG and only 32kb, whereas the JPEG version is 155kb - this is because JPEG excels at saving images with gradients and colour bleeding (it was developed for saving photographs, after all), but if you have "artificial" blocks of solid colour in your image (like the one I just linked to), PNG totally wipes the floor even if the image dimensions are huge.
Here's a document I wrote a while ago on file formats that may be of some use to you. I haven't updated it recently since it was for an old project I'm no longer with (and I remember all the info, so I don't need it XD) For anyone reading it, disregard the part in the "how to save" section for JPEG... there's a descrepency between JPEGs saved from "save for web..." vs "save as..." which may be caused by chromo subsampling being applied to the former (and unannounced, no less - thanks, Adobe!). So yeah, you might not want that, so use the normal "save as..." option.
I've actually thought of releasing all the documentation I've written in the past in case it's of some use to someone, but some of it is still a bit messy and might just end up being a hindrance / confusing >.>
Ran08 wrote:Actually, the file size thingy was because of a complain from a friend of mine. Wahaha. She said that she doesn't like downloading large files because it takes a long time.
That's understandable. I used to have a painfully slow connection just a few years back and still remember the frustration XD Out of curiosity, I resized the render I linked to above and made it 800 x 600, saving as a PNG. It's still almost double the size of the 1920 x 1200 version. The JPEG is 180kb and the resized PNG is 320kb. Anyway, bla bla bla, happy saving!
Edit: someone informed me the link to the image in this post was broken; it should be fixed now.