Some users may find that they accidentally selected the wrong gender after creating their accounts. Luckily, there are ways that this can be fixed.
If this has happened to you, you can change your officially registered gender by editing it in your account settings page. You can get to your settings by clicking on the gear in the upper-right corner of your screen and selecting Settings in the menu that pops up. This, however, will only change how the account is registered with Roblox and will not change the way your avatar looks.
To change your look, you'll need to pick up the free man or woman avatar packages from the catalog by going to one of the following links:
After you have obtained the correct package, go to the Avatar page. Once you're there, click on Packages in the list of categories on the right of the page. Find the correct avatar and click the blue Wear button next to it. Your avatar should now update.
Note: If you click Wear and the individual parts appear under the Currently Wearing section but your avatar does not visually change, click the "Click here to re-draw it!" link to force the update.
For more information on account and avatar customization, please see the following links: