how do you add a title with the Toshiba DVR620?

The manual may not be as "clear" as you would like,

but the fact remains that it is the best available guide

to successfully operating the machine.

Don't be afraid (or too cheap) to risk wasting a few DVD-Rs

in the process of learning how to do things.

Simply do what the manual says, one step at a time.

Update: I had a look at the pdf version of the manual online.

Its instructions on how to add titles seem perfectly clear to me.

If you can't figure it out from the manual, no one can talk you through it on a forum such as this.