How to send external form in backbone and rails app

I have a app with backbone in frontend and rails in backend. They are connected via api. I need implement form which will send to salesforce without refresh page. But I don't know how to do it.

The form looks like:

<form action="" method="POST">

    <input type=hidden name="orgid" value="xxxxxxx"> 
    <input type=hidden name="retURL" value="xxx">

    <input type=hidden name="xxx" id="xxx" value="xxx">

    <label for="name">Name</label>
    <input id="name" maxlength="80" name="name" size="20" type="text" required=true/><br>

    <label for="email">Email</label>
    <input id="email" maxlength="80" name="email" size="20" type="text" required=true/><br>

    <label for="description">Question</label>
    <textarea name="description" required=true></textarea>

    <input type="submit" name="submit">

Firstly, I tried to directly send the form via ajax, however, the js is not allowed to send the external url request. Access-Control-Allow-Origin will raise.

Then, I tried to send the request to backend firstly, and then send the post request to salesforce. However, I don't know how to do it in backbone.

Where to put the logic in backbone? In View, or Model, or Collection?

Should I create a separate controller in rails to handle the request? Or just an action method is enough?

Could someone tell me the best solution and provide me a simple example?