Here are some basic functions that e-mail clients provide to help you manage your e-mail:

Message Rules
Most e-mail clients support messaging "Rules." Rules are commands that the client executes when sending/receiving messages. Rules can move messages from one person, to a special folder, or delete unwanted messages as they come into your mail-box. Consult the "Help" section of your e-mail client on how to use this function.

Deleting
Deleting messages is an important part of keeping your mail-box uncluttered and easy to filter through. Deleting messages is simple. You will find a "Delete" icon in the tool bar, or you can "Right-click" on the item and go to "Delete". Multiple deletions are handy as well. To delete a consecutive list of messages (one after the other) select the first message, hold the "Shift" key, and select the last message. You will see that this highlights all of the messages. You may then delete them. Choosing multiple e-mails that aren't consecutive is nice as well. Select the first message, hold the "Ctrl" key, and select each message one at a time. You may then delete your selections by using the delete key.

Folders
Folders are used in e-mail just like they would be in any other part of your computer. How your e-mail client makes folders will vary. It is advisable that you search the "Help" section of your client for keyword "Folder" to learn exactly how your client makes a folder.