This is a feature of 6.2
This should work for 6.1 Someone with PHP knowledge might be able to help better. In showprofile.tmpl after
<td align="right" valign="top" rowspan="12">
<img src="$Picture" alt="Picture" width="$width" height="$height" />
</td>
</tr>
add this:
<tr>
<td class="darktable">
Member #
</td>
<td>
$User
</td>
<tr>
Now where I am fuzzy on since I do not have a copy of 6.1 to be sure of is if the U_Number variable which is called for is specified. You will most likely have to define it by something like this. There is a query that calls the user information. It will look something like this.
$query = "
SELECT U_Username,U_Fakeemail,U_Name,U_Totalposts,U_Homepage,U_Occupation,U_Hobbies,U_Location,U_Bio,U_Extra1,U_Extra2,U_Extra3,U_Extra4,U_Extra5,U_Registered,U_Picture,U_Title,U_Status,U_Number,U_Rating,U_Rates,U_Picwidth,U_Picheight,U_BirthMonth,U_BirthDay,U_BirthYear
FROM {$config['tbprefix']}Users
WHERE U_Number = '$User'
This is from 6.2 so do not try and do a search on this exact text. But you see what you need to do.
6.1 probally has
WHERE U_Username = '$User'
You need to make sure under that query that it reads
WHERE U_Number = '$User'
Backup both files before you try this and let me know if it works.
Now I would think you could place this in
