Where is the paste button on the iPhone keyboard?

On iPhone, you can select text by holding down on the words you want to highlight. Let go, and then tap on the text. This menu will show up:

Alternatively, you can use gestures:

Pinch with three or more fingers to copy, spread with three or more to paste.

Hello,

The black button (right icon) is the paste button.

When you touch that button the copy and cut button will show up if you select a text.

Give it a try.