Selecting more than 1 item on drop down menu ??

[Novice Computer User]

I have a drop down menu where people are able to select 1 item.
However, I want to modify the drop down list so that the person can
select more than 1 item (i.e by holding down the shift button and
highlighting multiple items). Can somebody please let me know how to
modify the php code so that they can select more than 1 item at a
time?? Thanks greatly in advance.

Here is the applicable .php code I believe from 2 different files:

FILE #1:
<tr>
<td align="right">Legal Category #1:</td>
<td><?=ptypes($_POST['primary_specialty'], "primary_specialty")?></td>
</tr>
----


FILE #2:
$q1 = "insert into legal_members set
username = '$_POST[NewUsername]',
password = '$_POST[p1]',
firm = '$my_firm',
primary_specialty = '$_POST[primary_specialty]',
secondary_specialty = '$_POST[secondary_specialty]',
gender = '$_POST[gender]',
FirstName = '$_POST[FirstName]',
LastName = '$_POST[LastName]',
address = '$my_address',
city = '$_POST[city]',
state = '$_POST[state]',
country = '$_POST[country]',
phone = '$_POST[phone]',
cellular = '$_POST[cellular]',
pager = '$_POST[pager]',
email = '$_POST[email]',
website = '$_POST[website]',
law_school = '$my_ms',
college = '$my_rt',
graduation_year = '$_POST[graduation_year]',
memberships = '$my_members',
bio = '$my_bio',
military = '$_POST[military]',
birthyear = '$_POST[birthyear]',
picture = '$new_picture',
RegDate = '$t',
ExpDate = '$MyExp' ";

[Chung Leong]

It's not doable. A drop-down select box can't have the multiple
attribute. You will have to make it a multi-line select.

[Novice Computer User]

I'm a novice. Could you tell me how to do that? Pleeeeeeeeease.
Thanks in advance.

:)

[Chung Leong]

<select multiple size="5">
<option>Bobo the Clown</option>
<option>Jeff the Flame-eater</option>
</select>