Create Custom Tags

I would like to create some customs tags that I can use while writing a post. I post a lot of vb code and use <font> and <span> tags which I’d like to simplify.
I tried puting this in wp-layout.css
vbcode {
font-family: “Courier New”, Courier, mono;
font-size: 12px;
}
so that I could type
<vbcode>Dim x As Long</vbcode>
when composing. I was just trying to emulate the code tag to see if I could do it, but I really want something different (and a few more custom tags).
Obviously I don’t know what I’m doing. Is it possible to define my own tags in the CSS, and if so, how? Thanks.