i just joined & chose an avatar - but it didn't work - I not have one - I am a cloud with no avatar

[Rolig Loon]

Don't panic. You have a simple case of common bake fail.  It's very easily cured.  See the comprehensive instructions at http://wiki.phoenixviewer.com/fs_bake_fail

As background, our avatar appearance files are all stored in Linden Lab servers and downloaded to our viewer software as we log in.  That download takes a few seconds, so it is very common to have a cloudy appearance (the default) until it is finished.  Occasionally, however, the file can be corrupted during download or there can be reasons why it does not load properly in your client, so the "bake" fails and you remain a cloud. 

If this happens to you often, there are two possible causes.  You might have a damaged SL viewer, in which case doing a clean reinstallation should clear it up.  More likely, however, you have an unreliable Internet connection.  Bandwidth is almost never a problem, but an unreliable connection can lose data packets or can have periods of slow transmission.  Either will result in poor loading, inventory loss, lag, and login difficulty.  Reboot your modem and router, which are often the culprits.  Also, avoid using a wifi Internet connection, which is neither supported nor recommended by Linden Lab. Use a direct cable or DSN connection.

 Oh, and welcome to Second Life. 

[Rolig Loon]

Don't panic. You have a simple case of common bake fail.  It's very easily cured.  See the comprehensive instructions at http://wiki.phoenixviewer.com/fs_bake_fail

As background, our avatar appearance files are all stored in Linden Lab servers and downloaded to our viewer software as we log in.  That download takes a few seconds, so it is very common to have a cloudy appearance (the default) until it is finished.  Occasionally, however, the file can be corrupted during download or there can be reasons why it does not load properly in your client, so the "bake" fails and you remain a cloud. 

If this happens to you often, there are two possible causes.  You might have a damaged SL viewer, in which case doing a clean reinstallation should clear it up.  More likely, however, you have an unreliable Internet connection.  Bandwidth is almost never a problem, but an unreliable connection can lose data packets or can have periods of slow transmission.  Either will result in poor loading, inventory loss, lag, and login difficulty.  Reboot your modem and router, which are often the culprits.  Also, avoid using a wifi Internet connection, which is neither supported nor recommended by Linden Lab. Use a direct cable or DSN connection.

 Oh, and welcome to Second Life. 

[Whirly Fizzle]

In the top menu bar of the viewer, go to Me -> Choose an avatar.

Choose any of the avatars here & click "Select".

Your avatar should then rez & you can then start changing your appearance.

[Lindal Kidd]

You actually have two separate problems.

First, the cloud issue.  This is called "bake fail" and can be due to any of several causes.  The most common reason is a poor internet connection.  The others have given you links to more information on how to solve this, so I won't repeat them.

The second issue is the avatar you bought.  Once you solve your bake fail problem, you'll notice that your avatar is partly naked, partly invisible, and has a sign or a box attached to its right hand.  This is because you replaced your initial "starter" avatar  with the box containing the avatar that you purchased.

You can put any of the starter avatars back on.  Click the Avatars button in the left toolbar and select one from the gallery, or open your inventory and find Library\Clothing\Initial Outfits.  Then drag the folder of any of the avatars there and drop it onto yourself.

Then you can proceed to open your box and extract the contents, so you can wear your HFL Axis avatar.  See this link: https://community.secondlife.com/t5/English-Knowledge-Base/Opening-boxes/ta-p/700185