I think you can also go into CAS within the game (i.e. from the dresser) and click on the share option (under the button with ... on it) That will allow you to upload it to EA's sims 3 official website under your profiile. That way you will also have a copy that's in a different location to your hard drive, in case of crashes, hard drive meltdowns, etc.
I haven't fully tried this yet, i've only shared the sims and they are in my uploads section in the game launcher waiting to be uploaded.