Contact Form 7 styling

Hi all,

I’m not realy a experienced programmer but i’m running in to some diffuculties.
i’m working with the wordpress template total. There was a standard contact form within contact form 7.

This is the code:
<p class=”one-half first”>[text* your-name placeholder “Naam”]</p>

<p class=”one-half”>[email* your-email placeholder “E-mail adres”]</p>

<p class=”one-half first”>[tel your-tel placeholder “Telefoonnummer”]</p>

<p class=”one-half”> [radio contactformulierkeues default:1 “Particulier” “Zakelijk”] </p>

<p>[textarea* your-message placeholder “Typ hier je bericht…”] </p>

<p>[submit “Verzenden”]</p>

It’s working fine, but the problem is, when i want to add a drop down or radio buttons the whole styling get’s scrambled. and i don’t know where ican find the class”one-half”

I’m really stuck … can anyone help me please?