SharePoint makes its own buckets I think it is twenty
per level.
If you want to add pages do it with the SharePoint
Portal. Go to Manage Portal site and you can add
content there ...I would not add my own buckets...why
are you doing that...?? You can add them for images
etc.

I'm letting SharePoint manage all the buckets its just that I was
told that there are 3 open buckets on the intial install but we only
had 2. I was wondering if I got the wrong information.

It is my understanding that SharePoint Portal makes
its own buckets. How many and how is up to sharePoint.
I don't think you have to worry about how many buckets
there are unless you are having problems.

It does indeed. The easiest way I find to think about this is to imagine
a 20*20 grid. As portal areas are created the first row of this grid is
filled until it is complete. When the 21st area is created 19 buckets
are created for rows 1-19 and then the grid starts  to fill by row. So
the 21st portal area is /c0/area, 22nd /c1/area etc. Microsoft did this
to avoid having too many URLs at the same "level".

Now when an area is created the first free slot in the grid is used.
Therefore if you really want to have a portal area with a "clean" URL
you could always delete one of the first 20 areas in order that the next
area you create  will go into the first row of the grid.

could you please explain a bit  further the following:

"Now when an area is created the first free slot in the grid is used.
Therefore if you really want to have a portal area with a "clean" URL
you could always delete one of the first 20 areas in order that the next
area you create  will go into the first row of the grid."

Are you saying that it is possible to have more than 20 top-level urls
(sites)?
bypassing the "C1", "C2" structure.
If so, what is the exact process to accomplish that?

No, what's he's saying is that the C1, C2 scheme has 20 "clean" URLs without the
Cx notation (mostly the OOTB areas). The scheme also "fills in the gaps" when
an area is deleted, so if you need a clean URL you can get one by deleting an
area using one of those clean slots, then creating a new area immediately.

No I am not saying that. What I am saying is that you can control what
areas are in the first 20. If one of the first 20 is free then it will
be used for the next portal area that is created.

yup, that is the conclusion I came to myself, just wanted to confirm,
because language of your post was not entirely clear to me.