In the form for a new mail, select "Insert" -> "Signature" -> "Signatures".

With "New" you can create a new signature whose text you can enter in the text field below.

On the right, in the "Select default signature" area, you can specify whether and, if so, which of the created signatures should be used automatically when creating a new mail or replying to/forwarding a mail.

You can insert a signature manually into a new mail by selecting the "Signature" button from the "Insert" toolbar. You will then receive a selection of available signatures.

It has become an established convention to separate the signature from the message text by "--" (two hyphens). It is therefore best to start your personal signature with a line containing only two hyphens.

Less is more: very long signatures are often perceived as annoying. Also, the readability or the overall impression of your signature should not depend too much on special text formatting or even image objects, because this information is lost if the recipient's mail programme does not allow the display of HTML mails (mails with images, text effects, etc.). Many companies prevent html display because of the increased risk of viruses.