What personal details you include on your profile are entirely up to you. The only required details are your name and your email address. Everything else is optional. While every effort will be mad to keep your personal details safe, understand that web sites get hacked all the time. Any site that tells you that your information is 100% secure, is lying to you. No promise can be made that this site will never be hacked, but some out of the ordinary steps have already been taken to reduce that possibility.
With all that in mind, it would be wise to never post content that would trouble you if the whole world knew about it. Use common sense and good judgement when posting content, and you'll be fine.