I have made a few short tutorials in the past, this one is a little longer but it works with Alpha channels through the Gimp editing program (My version is 2.8!). There may be shorter ways to do it, but this one is foolproof in my years of experience.
So ultimately you will need:
- Gimp, or other photo editing program.
- OpenSim Game (this example was in SL, with the Singularity Viewer)
- About 5-20 minutes of time depending on your comfort with Gimp.
Ok so you've got your stuff, its all open, and you're ready to go.
I am making a few assumptions in this tutorial like, you know how to make a box in SL!
You've got that covered right? SO here we go!
1) You need to open up a new image.
2) Go to Layers > New Layer
3) Select the Transparency option
4) Click the eyeball next to the first layer (White layer) which will make it invisible.
5) Select your NEW LAYER.. If you feel like it, name it, but it's not important.
6) For this particular tutorial - I went ahead and just did a basic text transparency - but you can make something pretty if you feel up to that. To make a text box, hit the "A" icon in your toolbox. Make your box as big or as little as you want. Bigger makes it easier to read for larger walls. Smaller is more whimisical. I went crazy big just because. Play with what you want for your space.Type your message! GO on!
7) So you've got this beautiful message written and ready. You're gonna have to go ahead and Export this bad boy. Go to File>Export As.. Give it a cool name that you'll remember. Make sure to use an extension such as .TGA or .PNG which will keep the transparency. I like to save it to my desktop to make it easier to find - but save it wherever you feel comfortable. Make sure to hit Export..a little dialog will pop up and EXPORT again. It'll save to your desktop.
8) Okay, go into your game! You need to upload. I showed you the old fashioned way, but you can also hit CTRL+U and it should go ahead and pull up a window for you to pick your file out. Find that awesome alpha deco you just made. Load it up. Hit upload! Yeah! You did it!
9) Well almost. I mean, you got here. So you need to rez a box. Nothing else will make this look right. Make it nice and skinny and as big or as little as you need it to be! (This is where I go ahead and assume you know how to do this).
10) With build mode still open with your sweet skinny box, click the TEXTURE tab. Then under that preview window that's wood-like select ALPHA. This makes it all see through and stuff! COOL! Don't let go of it, or you'll have to go rooting around for it. (Ctrl+ALT+T will help you find it).
11) With it still highlighted, find that cool texture in your texture folder (should be right on the top) and drag..yep, select and DRAG it over to your prim. This will make it one sided. If you want it on both sides, just repeat it to the other side. Definitely don't just drop the texture into the box or it looks bizarre on the edges and not nice and clean.
12) Give your deco a name. I was really creative and called it WALL DECO. I know, right? Now you can take it in your inventory, change permissions, and put it where you want it!
Hope this helps. As always, I'm accepting tutorial requests - just send me an ASK! <3