Hey,
I found a lot of custom Arena posters, but nothing that I liked really. I'd like to make my own Arena poster. I Have paint shop pro, if it's needed. What else is needed. My friend as Photo Shop if this one is needed.
Link me a post about it or tell me what programs are required and how to create it.

Thanks a lot, I've been looking for days already.

You'll need a BSA unpacking program like BSA Commander to get the default texture, DDS Converter (or a DDS plugin for Paint Shop Pro), a program like OBMM for archive invalidation, (If that's the program you're going to be using to retexture)

First, use your BSA program of choice to find the Arena poster textures (To save you some work, the filepath is Textures/Architecture/ImperialCity/ICArenaPoster01.dds) and extract them somewhere you can work on them. I don't know how Archive Invalidation works, but you might also want to extract ICArenaPoster01_n.dds.
If you got DDS Coverter, convert ICArenaPoster01.dds into a format Paint Shop Pro can use and open that. If you got a DDS plugin for it instead, just open ICArenaPoster01.dds in Paint Shop Pro. Looking at the texture, since it's mostly a single 2D plane, it should be pretty clear how any changes you make will affect the poster in-game. Change it however you want.
Save it as a DDS if you got a plugin, or turn your new texture into a DDS if you got DDS Converter. I know next to nothing about editing Normal Maps, so I can't help you if you want to change how light reflects off it...
Paste the normal map and the new .dds file in in Oblivion/Data/Textures/Architecture/ImperialCity, making new folders if necessary.
Open up OBMM, click Utilities, then Archive Invalidation, check "Textures" under File Types to Include, and click Update Now.

That should do it.

thx

I'd use the blank parchment normal map, unless the poster's supposed to be embossed. Ink shouldn't cause noticeable bumps in the texture. Wouldn't need to edit it, just give it the same name as your new texture, with _n appended.

I very much doubt the blank parchment normal map is the right size, and the Arena Poster normal map is already basically nothing but parchment anyways.

It's not the same size, no, but since it's just blank paper texture, that doesn't even matter. I used it myself for posters of many sizes in the mod I'm working on now, just so that light doesn't glare off them. You can see how they came out in this screenshot.

Oh, and I should explain that the reason I suggested the blank parchment instead of the original Arena poster normal map is because when I retextured the Grey Fox wanted poster, I noticed there was in fact some embossing of the original wanted poster visible in the normal map when the main texture was changed. I don't know that the Arena poster does the same thing, but I recommended the one that I knew for certain had no imprint.