As a Google Groups user, one of the first things you might want to do is read and respond to group posts. Depending on how a group is configured (and your personal settings), you will be able to read and respond to posts either through your google account or using email.
This process assumes that you have "Email" checked in the "How do you want to read this group?" section of the my Membership settings (you are receiving an email for every post to the group), and that you are approved to send messages to the group. Some groups are set up as distribution lists and only Group Managers can send messages to the group. Other groups are discussion lists so all members can send messages to the groups.
Read and Respond to Posts Using Email
Click on the email in your inbox to see the message from the group
Type a response to the email.
Select reply (to respond only to the poster) or reply to all (to respond to the whole group). The response is posted.
Read and Respond to Posts from your Google Account
Click on the 'My Groups' button on the Home screen. A list of all your subscribed groups appears.
Click on a group name. The Topics screen appears with a list of all current topics. Notice that all of the unread posts for a topic are listed (in bold).
Click on the topic you want to read. The first post in the topic (created when the topic was created) is displayed on top followed by all responses.
Click on the Post reply arrows in the right corner by the time/date of the post.. A reply field appears with a formatting toolbar at the top.
Tip: Click on the Post reply button (or the red Post Reply) in the first post to reply to the original topic creator. Click on Reply to Author under "More message options" to reply to the poster through private email. Click on Forward under "More message options" to forward the post to an email address.
(optional) Click the Quote original link to display the original message below your response.
Type your reply in the reply field.
(optional) Format your reply using options in the formatting toolbar.
Click the Post button to reply to that post.