From IceBB Wiki

Uploading files to attach in your posts is pretty simple in IceBB, yet many people still have problems with getting it to work. This is probably due to that many forum systems add a sort of list at the bottom of the post containing all of the attached files. However, IceBB does not work like that. Here you are given the opportunity to display your attachments inline using a BBcode. It gets even simpler than that as you are given a list of all your uploads where you can then click on it and the appropriate BBcode is added at the location of the (typing) cursor.

Uploading a file

First you need to find the file you wish to upload on your local computer. Click the "Browse..." and find the file, or if you know the absolute path, type it in the field called "From file:" under the "Upload a file"-section of the post page. Next click the "Upload"-button and your file is uploaded. See the top image on the left.

At the time of writing the list of attachments in v1.0 does not automatically update, so you will, unfortunately, have to refresh the page. Therefore you are encouraged to upload the files you need first to ensure that you will not loose any content of your post (even though it is unlikely that you will) when refreshing.

When your file has been uploaded and you have refreshed the page, then you will see your file in the "Your current uploads" section (see the image on the right).

When you have identified your file and clicked on it, then you will see that it will automatically add the BBcode for that file. The BBcode's syntax is like this:

[attachment=*upload_id*]

Since you are not able to know the upload id as it is a unique id that has been stored in the database of IceBB to be used internally, the file link will insert it for you.

This is all there is to uploading and attaching files in your post in IceBB.