Within Teamwork CRM, you can use custom fields to tailor the different forms to your needs.
You can customize the forms used to add new items for:
Custom fields can be created via the Customize forms section of your site settings.
For each custom field you create, you can choose whether to Show in add form.
When this option is selected, the field will be included in the creation form for the item type. You can also set the field to mandatory.
You can also rearrange your custom fields to update the order in which they are displayed in the add forms. In the Customize forms section of your site settings, click and drag the move handle to the left of the relevant field and drop it to a new position in the list.
For more information, see: Creating Custom Fields for Leads and Opportunities