How to make bootup logo?

I got a picture,and i uploaded it to big file,changed nbalogo.fsh but it ain t working.What is the problem?

It's a bit hard to say, as that description of the process is a bit vague. Editing logo and frontend screens is a fairly straightforward process though:

1. Get .big file.
2. Export the necessary .fsh file.
3. Open .fsh file in FshX, import new texture. Be sure to save it.
4. Import .fsh file back into the .big file.
5. Place updated .big file in the sgsm folder.

I prefer to use BigGui for exporting and importing the .fsh files from .big files.

If you're following those steps then everything should be working fine. It's difficult to say what your actual problem is, because "it ain't working" doesn't tell us very much, such as the original texture still displaying, no texture displaying or the game crashing. I'm guessing the new texture hasn't been imported properly or the .big file has otherwise been damaged. Again, without more of a description of how it isn't working exactly, it's difficult to answer that question.

i have done all of that,but nothing shows.It s just basketball from default live 08 screens,but withount logos.Maybe i should change nba logo.ebo too? I ve just changed nbalogo.fsh,i ve used JHiane s big file.Can you make it? I will give you texture,it s from 2k13,original i took a pic

No, you shouldn't have to edit the .ebo file at all. If you've followed all those steps correctly, then I don't know why it isn't showing up.