I am trying to create nice looking curves with InDesign, but I can't get a good result using the Pen tool.
What I want is something like the curves in the following pictures on top and below the title text:
I'd hazard a guess that in 99.5% of uses such as this those flourishes are not drawn or created.
Rather they are decorative glyphs found in any number of fonts.
Here's one such font: http://www.myfonts.com/search/fleurons/fonts/
Simply pick the glyph you want and set it like you would any type character.
If you really want to draw your own, it simply takes practice with the pen tool.
Those specific ornaments are part of Bickham Script Pro, which either came with your copy of InDesign (if you have a perpetual license version) or can be installed from Typekit (if you're on Creative Cloud).
Many OpenType typefaces include ornaments. To find them, use the Glyphs panel (
Type > Glyphs) and use the dropdown selector to view "Ornaments" and "Private Use Area," which are the usual places to find them.
In many cases, your best bet is to use an ornament that is built into the typeface you're using. You can also find flourishes, fancy corners, swirls, swooshes and other decorative elements of varying quality on any stock image site or some of the freebie sites. Just Google variations on "ornamental graphic" and you'll find lots.
If you want to roll your own, InDesign, versatile as it is, is not the right workshop to be doing it. Illustrator has many more tools for this kind of work, and if you have an iThing, the new Shape touch app includes many drawing aids such as French Curves to make the job of creating that kind of curve much more accurate and straightforward.