To help them to get to know you, tell your step-children about your past. Show photos of you growing up and of your accomplishments. Show them awards you may have won or diplomas/degrees you've earned. Maybe, take them and show them where you grew up. Let them know the whole you - they probably haven't seen too much so far and don't really have a complete picture of you. However, you may wish to keep your skeletons in the closet - you don't want to scare them as they may be wary of you at first until they are comfortable.