As such, having some knowledge of it beforehand is highly recommended.
Careless use of dselect can wreak havoc on your system.

dselect will step you through the package installation process outlined
here:
1. Choose the access method to use.
2. Update list of available packages, if possible.
3. Select the packages you want on your system.
4. Install and upgrade wanted packages.
5. Configure any packages that are unconfigured.
6. Remove unwanted software.
As each step is completed successfully, dselect will lead you on to the
next. Go through them in order without skipping any steps.

Here and there in this document we talk of starting another shell. Linux
has six console sessions or shells available at any one time. You switch
between them by pressing Left Alt-F1 through Left Alt-F6, after which you
log in on your new shell and go ahead. The console used by the install
process is the first one, a.k.a. tty1, so press Left Alt-F1 when you want
to return to that process.

Once dselect Is Launched

Once in dselect, you will get this screen:

Debian Linux `dselect' package handling frontend.

0. [A]ccess Choose the access method to use.

1. [U]pdate Update list of available packages, if possible.