If you want to put a link to your email address on your site you can, but it leaves your address vulnerable to SPAM.  To do it highlight the text you want to use, click Insert, select Link, select Web address and enter your email address.

You can email me directly at bobk8oms@gmail.com

If you don't want to put your email address on your site you can use a contact form like described below 
which hides your email address.

This form is supplied by allForms (http://allforms.mailjol.net/)
When you use this form on your site it will send you an email which you can reply to.
The Send a File link is optional.

First create a form at the allForms site. In the information page for your form see "The direct address of this form is: http://free.allforms.mailjol.net/u/xxxxxxx.php" Copy the address for use in the steps below.
Here are the steps to insert the form on a page hosted by Google Sites:

1. Open your Google Sites page for editing.

2. From "Insert" menu, choose "More Gadgets".

3. On the "Setup your gadget" popup window click "Add gadget by URL".

4. Add your form's URL appended by "?googlesites". For example if your form's address is:


Enter: http://free.allforms.mailjol.net/u/xxxxxx.php?googlesites as the Gadget's URL. Remember to replace the xxxxxx with your own form's number and add ?googlesites to the end.

5. Uncheck "Display title on gadget" box and adjust height and width to values which displays your form best.

6. Click "OK" to embed the Gadget and finally save your page.