How do i add custom fields to my check out process?

[jjj2k]

In my creditcard.tpl I want to add a new checkbox for user to tick he/she understands the billing and authorises us to log their IP.

 

How do I put it after this section?

 

{if $shownostore}

<tr>

<td class="fieldarea"><input type="checkbox" name="nostore" id="nostore" /></td>

<td><label for="nostore">{$LANG.creditcardnostore}</label></td>

</tr>

{/if}

 

 

Just duplicate this ?? But how/where do I define the variable, eg. $showconsent ??

 

also i want the users IP to be written to the tblinvoices "notes" column, how do I do that? Any help is much appreicated.