Hii,

Here is example to to add 2 or more columns 
<group col="3">

    <field name="field_1"/>

    <field name="field_2"/>

    <field name="field_3"/>

    <field name="field_4"/>

    <field name="field_5"/>

    <field name="field_6"/>

</group>

i hope it is usefull

Go into developper mode when you are in studio

 then tab view 

and button xml 

Hi,

You can add more than 2 column in the form. For adding 3 columns in the form, you can do coding as follows.

Thanks