While in either command mode or in search mode, type Ctrl+R" to paste from the default register. That is, type Ctrl+R, release it and then type ".
For any other named register, you can just to Ctrl+R followed by the name of the register, like a
or b
.
Alternately, if you enter search mode using the command q/
instead of just /
, you can simply use p
to paste, the same way you would in a normal buffer.