Someone help me I put the pex on my server 1.8 ai when I close the server I open it disappears

Show me your console log. Copy it to Pastebin.

as well?

Copying stuff to Pastebin is typically how things are shared in the Minecraft community. Since you seemed extremely new to Minecraft servers (no offense meant, everyone was new at one time), I figured I should mention Pastebin in my previous post.

Could you send me a tutorial on how I put the files there? Because I do not know

You don't know how to copy and paste text?

Yes I know

Copy the text from your server console and paste it into Pastebin. After you click "Create a New Paste" at the bottom of the screen, you will see your paste with its own link at the very top of your browser, in the address bar. Copy that address and paste it into this thread.

http://pastebin.com/D3UHwGKg

[21:03:24 WARN]: **** SERVER IS RUNNING IN OFFLINE/INSECURE MODE!

PermissionsEx does not support servers running in offline mode. You will need to change the server.properties file setting to online-mode: true before PEX will function properly and then I can help you more.

But if I put online-mode I do not have original minecraft

Sorry. I can't help you with that. PEX doesn't support hacked/illegal copies of the Minecraft client or servers.