Arguugh ... there you go with that "the FTP userS again. Note that I said "If "just 1 will do" ... you can do what you want using the "remap a subdir" method". This will not help you if you want more than a single FTP user to do this.
While I'm not sure I can make it anymore clear than the wiki articles I linked you to before, I can try:
1) Create the new FTP user that you want to be able to access a given directory in your website. - for an example, let's call that new FTP user "user2"
2) Create a directory in your website that you want that user to be able to access via FTP - for an example, let's name that new directory "user2stuff" (which would be reached on the web as "http://www.yourdomain.tld/user2stuff/")
NOTE: It doesn't really matter if you do step 1 or step 2 first here, and you don't have to do them at all if you already have created the FTP user you want to be able to access a directory in your site and you already have that directory recreated, but you do need both of these things in place before proceeding to step three!
3) Then go to the Panel -> Re-map Sub-dir screen, and complete the provided forms.
4) In the first screen, fill in the "Fully-hosted URL to remap:" to describe the url you want to be now accessible to the new, or other, FTP user, and hit "Continue" - using our examples created in steps 1 and 2 above, you would use the pulldown selection list to select your domain, and put "user2stuff" in the "box" beneath the selection list.
5) In the second screen, you will see that your choice from the first screen for the url to re-mapped listed (if it is not what you want, go back to the first screen and correct it now!), another pulldown selection list from which you can choose the other user (in this case, you will choose "/home/user2/", and a suggested directory structure to use for your remapped sub-dir in the selected FTP user's directory. -
Using our examples you would see "http://www.yourdomain.tld/user2stuff/" for the "Url to re-map", you would select "yourdomain.tld/user2stuff" from the pulldown selection list, and as the "suggested" directory to use in the other FTP user's directory you should see "yoursite.tld/user2stuff. You can leave this last part "as is" (which I recommend so that it is easy to keep straight what website will server that dir), or change it if to whatever you want.
Okay - that's the "really long version" of how to "Re-map a Sub-dir" with, I think, every base covered. (I like the wiki version better!)
Just don't forget that:
1) This allows exactly 1 other FTP user to manage the contents of that dir
2) If you want to manage the dir, you will either have to set up appropriate user permissions to allow that (which is complicated and, IMHO, a potential security risk - particularly if yuo are not confortable with unix permission, groups, the shell, etc.) or just log-in as the other FTP user when you want to manage the files (which is what I highly recommend - it's your account anyway!)
3) You will not be able to run CGI scripts or PHP (DreamHost default to PHP-CGI) from this directory because of permission issues related to DreamHost's suExec security enhancement.