To forward an individual message 

1. Open the appropriate conversation and select the message to forward. 
2. Click Forward from the bottom of the message card. 
3. Enter the email address(es) to which the email should be forwarded, and add any notes in the message field. If the message has attachments, you can choose not to forward them by deselecting the checkbox next to the filename below the Subject field. 
4. Click Send. 

To forward an entire conversation  

1. Open the appropriate conversation. 
2. Click Forward all from the right side of the Conversation View. 

Forwarding an entire conversation will add all messages from a conversation into a single message. Each message will be clearly marked, and will be listed in order from oldest to most recent. 

To forward an inline image  

1. Open the message you'd like to forward. 
2. Click Forward along the bottom of the message. 
3. Click Rich formatting >> above the text field of the message you're forwarding. 
4. Click Send. 

Gmail also lets you automatically forward incoming mail to another address, if you'd like.  This is demonstrated below: 

Here's how to forward messages automatically 

1. Sign in to Gmail. 
2. Click Settings at the top of any Gmail page, and open the Forwarding and POP/IMAP tab. 
3. Enter the email address to which you'd like your messages forwarded. 
4. Select the action you'd like your messages to take from the drop-down menu. You can choose to keep Gmail's copy of the message in your inbox, or you can send it automatically to All Mail or Trash. 
5. Click Save Changes. 

You also can set up filters to forward messages that meet specific criteria. You can create 20 filters that forward to other addresses. You can maximize your filtered forwarding by combining filters that send to the same address. 

Note: At this time, you can't select from your Contacts while forwarding a message.