comment style (your contract)

you asked for layman comments and this shape:

c# line comments: //comment
lowercase after //
no space after // unless you must for readability on long lines
do not restate what the code says (//increment i). say why or what was confusing.

c# examples (style only)

//map null payment to "still open" in the ui
if (order.PaymentTypeID == null)
{
    //...
}

//ef needs this navigation or details page will null-ref
.Include(o => o.OrderItems)

razor files are mostly html. server-side comments use razor syntax:

@*hide closed orders on home*@

avoid // inside pure html (browsers may not treat it as comment). inside @{ } blocks, // is c# again.