This looks simple but can be tricky sometimes when
you use different apps. In general, these steps can be
used in Mail or some other apps:
1. Double-tap to select a word, or tap
once with two figures to select a
paragraph. (Note)
2. Drag the handles to adjust the
area if needed, then select Cut or
Copy.
3. Tap an insert point then tap the
cursor, or more directly, touch and
hold an insert point.
4. Select Paste.
Note: Step 1 doesn't work in a browser like Safari
since "double-tap" has been used to enlarge a
webpage. Instead, use "touch and hold" to copy text
or an image. If "touch and hold" shows a block on a
certain webpage, try "tap and touch-and-hold".