While it is difficult to tell from your picture, it does look like a fungal infection. You can get an anti-fungal from any Big Box store or garden center; just ask someone in the store.

The other thing that will help you posting pictures is to use one of the features in Photobucket. When you want to post a picture that you've uploaded to PB, simply click the 3rd item down on the list under the picture. You will see "copied" for a brief moment. Now go back to your post here at C&S and right click your mouse and select "paste". When you "Preview" your message you will see a picture and not link.

The other thing I neglected to mention is that if this is only on a leaf or two, just remove the affected leaves. I would spray only if you see other portions of the plant becoming infected. So why is this happening? Could be too much moisture (humidity) and and not enough air circulation. Just a thought...

1) Depot your plant - it's suffering from non-porous soil, too much watering, not enough warmth and not enough sun, but mainly the first two.

2) Get some perlite and cut your potting soil with 50% perlite and repot in fresh soil. Don't water for a few days (if then, depending on the condition of the roots). In those few days, spend some time here reading posts on jade / Crassula ovata, and plant nirvana will be yours.