Insert checkbox values to database separated by commas

On my .cshtml file, I have this form with checkboxes:

<div class="checkbox">
    <label>
        <input type="checkbox" value="Clothing" name="Child1GiftTypeNeed" checked>
            Clothing
    </label>
</div>
<div class="checkbox">
    <label>
        <input type="checkbox" value="Shoes" name="Child1GiftTypeNeed">
            Shoes
    </label>
</div>
<div class="checkbox">
    <label>
        <input type="checkbox" value="Coat/Jacket" name="Child1GiftTypeNeed">
            Coat/Jacket
    </label>
</div>
<div class="checkbox">
    <label>
        <input type="checkbox" value="Books" name="Child1GiftTypeNeed">
        Books
    </label>
</div>

How do I insert the value of these checkboxes in one single database column separated by commas?

(I am a brand new C# learner)

This is my insert from codebehind:

[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult Index([Bind(Include = "Id,Child1GiftTypeNeed")] HGProgram hgProgram)
{
    if (ModelState.IsValid)
    {
        //Save to my database
        db.HGPrograms.Add(hgProgram);
        db.SaveChanges();
    }
}