MyBB Community Forums

i want to add my FORUM a PDF 5M what i to do ?

I'm not entirely sure what you mean. Could you explain it with a little more detail?

I have a PDF file that I want to add to My MYBB Forum
But he will not let me add, in Configuration -> attachment_types to 2M, what to do so I can i add PDF 5M!

Change the Maximum File Size (Kilobytes) to something like 6000. Please refer to MyBB Wiki: Config Attachments.

It says

The maximum file size for uploads of this attachment type in Kilobytes (1 MB = 1024 KB)

Please ensure the maximum file size is below the smallest of the following PHP limits:
Upload Max File Size: 2M

ACP>Configuration>Attachment types

This as nothing to do with MyBB, please read:
https://www.dokuwiki.org/faq:uploadsize

does he need to change maximum file upload size in apache hpptd.conf ..??