Create a Custom Field
Lets call ours "Type" so that we can sort our customers according to business type. First log in to your portal via the admin username, then click settings, Custom Fields. Now you will need to choose the module you wish to add this field to. For ours we will use "Contacts" so click the pull down labeled "Select Module" then click Contacts. Now select "New Custom Field" Now you choose a Label and type, enter "Type" and lets use "Multi-Select Combo Box" now you are presented with "Pick list Values" enter the types of contacts you want available. We will use Business and Personal now just hit save. Congrats you made a custom field.
Find the Custome Field Number
Because vtiger names the table in sql cf_"ascending number" instead of the label you typed you have to find the name of your new field. To do this you need to be logged into the vtiger portal and in the module you created your custom field in, for ours we log in the select sales, contacts or marketing, contacts. Make sure that you see you custom fields, you may need to create a filter that includes them. To do this you need to click by filters where is says new, just select a few fields along with your custom fields. Put in a name and hit save. Then you are taken back to the screen where you have your contacts under filters select your new filter .On a pc or linux machine you can right click, on a mac cntrl click to right click and select view source. then search for "cf_" you will turn up something like
<option label="Type" value="cf_488">Type