ChelseaDT explained it well:

You can do this in your condo , this is where you first go to when you log into the game.

Click on the mirror in your condo and then under the “body” tab simply click on either the male or female (in this case female) and this will change your avatar to female

Also please remember to click save in the top right corner once you have seleted female so it will save.

Please let us know if you encounter any other troubles.