This is one of these small things it could take you a while to figure out. In your “Text” tab, what you want to do is type:
$latex your-latex-code-here$
For example
$latex \gamma$ would give you
$latex \gamma$.
So what could go wrong?
If you mistakenly put space in after the first dollar sign. e.g.
$[SPACE]latex \gamma$
Then you will get the latex code on the screen. (Argh.)
Her are some more complicated examples:
$ latex \int_0^1 f(x) \, \mathrm{d} x $ is
$latex \int_0^1 f(x) \, \mathrm{d} x$
And
$ latex \displaystyle \sum_{n=1}^\infty \frac{1}{n^2} = \frac{\pi^2}{6}. $ is
$latex \displaystyle \sum_{n=1}^\infty \frac{1}{n^2} = \frac{\pi^2}{6}.$
I think this is a useful thing to know because if you copy latex formula from the web it would take you a while to get it right and nice.
Arthur