Straight Tapered Dart
First, you need to transfer all your markings from the pattern to the fabric. The Book emphasizes this importance over and over It suggests using an awl, if you have one. I do not. I didn't have a pattern, either. In fact, to make things stand out more in the photographs I used a magic marker. Pretty sure the Book wouldn't like that.
On the wrong side of the fabric mark the end of the dart tip (the top dot, center) Mark another point 1/2 inch down from the dart tip (second dot, center). Mark and snip the ends of the dartlines (two points at bottom, to either side of bottom center mark)
Fold fabric, right sides together at center dart tip, and matching snip to snip at bottom (snip to snip-ha ha)
If you want, mark the stitchline you'll need to follow from snipped ends to dart tip. Pin if necessary.
Sew from top dart mark, making sure to sew along the edge of the fabric fold a stitch or three. Backstitch. Sew to snip mark. Backstitch.
Clip threads. I thought it was funny the Book said to do this. You know, because otherwise you'd just leave 'em hanging.
Now it's time to press. I've mentioned tailor's hams. Here is where one would be handy.
Note that the dart makes the fabric curve and have shape. Ironing on a flat ironing board would cause puckering, etc.
I don't have a tailor's ham (YET!) so I used a tightly rolled towel.
Use a piece of paper in between the dart excess and the rest of the fabric. This prevents impressions on the excess fabric from appearing on the right side of the fabric. Press toward center. Or in my case, where ever I wanted.
The Book says: "The Straight Tapered Dart is the basic dart styled in a bodice, skirt, or sleeve to give a smooth rounded fit."