Haha this is the same tutorial that I copied from
my site 
Things you'll need:- PSP (any version or type)
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PSP theme creator - Photoshop (recommended)
Part 1: Getting Started1. After you've extracted the archive open themeconv.exe
2. You will be on the "information" tab.
Title: You know what to do here xD
Product ID: Can be both numbers and letters
Version: Numbers only (and dots ".")
3. Moving on to the wallpaper tab.
4. After you've clicked on the Wallpaper tab you'll see an empty block. Select the file icon and locate your wallpaper.
The wallpaper size has to be 480 x 272 and in 24 bit map (.bmp) format.
This is a 480x272 24 bit image
Part 2: Icons1. Click on the Category Icons tab. Click on the file icon and locate your image.
The size of the category icons should be 64x48 (width x height that is) and they should be of a 8-bit png format. To do this on photo shop, locate your icon file and make sure it's size is 64x48. Then click on File > Save for web and from there at the top right you'll see a bit that says "Preset" change it to "PNG-8 128 Dithered" and click save. You can now use that image as a Category Icon.
2. Now we will be moving on to First Level Icons. For this you can use the default, which will make all the First level icons the same. You'll notice there's two empty blocks now, the Icon body and Icon focus.
For the icon body, the image size should be 48 x 48 and 8-bit png format To convert the image into an 8-bit png read Part 2, Step 1 above^. For the icon focus this can be a bit tricky. We're going to use the same image we used for the Icon body. Now on Photoshop, click on the Image tab and select "Canvas Size" Change
the Canvas Size to 64x64 pixels and click ok. (The image size will remain the same that is 48x48) Now Select the Filter tab > Blur > Blur more. Keep using this image until the file gets really blurry.
After that click on save for web as PNG-8. (Do not overwrite the Icon body! so you should consider changing the file name) Now you can use this image as the icon focus. (Take note that both the Icon body and focus should be an 8-bit png image)
3. Moving on to Second Level Icon tab. You can use the same step above^ but there will be changes in size.
For the Icon Body the image size should be 32 x 32 and an 8-bit png. For the Icon Focus the Image size would be the same (32 x 32) but the Canvas size would be (48 x 48) with the same blurry filter and an 8-bit png format. The blurry filter is used to make the icons glow or highlight.
Part 3: Finishing up1. At last we're here! We're moving on to the "Others" tab.
2. The Preview icon the image size should be 16 x 16 and in a 8-bit png format. Refer to Part 2 for converting it into 8-bit png.
3. For the Preview Image, the file size should be "300 x 170" and in a 24 bit map format. Refer to part 1 for converting it into a 24 bitmap image.(you can re-edit the same file you used for the wallpaper, make sure you don't overwrite the file though!)
4. The theme color doesn't matter, I just set it as default which is by month xD
5. Now that we've done everything click file > export (or you can just press f5) You can name it whatever you want. Now locate the PTF theme you just created and move into your PSP via usb mode (PSP Folder>theme)
