Animating an object is done by applying keyframes to the parameter you want to change. In your case, you want to set two keyframes for the x coordinate: one at the beginning of your clip, with the object off the left side of the screen ,and one at the ned of the clip, with your object off the right side of the screen. Open the **** system for FCPX and look for Video Animation. If you have no experience controlling animation, the concepts of keyframes and eases and motion paths can be quite confusing.

Video animation overview

With Final Cut Pro, you can create simple changes to video over time, such as fading the video from invisible to visible at the beginning of a movie. Or you can make sophisticated and precise adjustments over time to many individual parameters of video effects, transitions, motion paths, and so on.

In Final Cut Pro, you use keyframes and fade handles in the Video Animation Editor to change effects over time.

The word keyframe comes from the traditional workflow in the animation industry, where only important (key) frames of an animated sequence were drawn to sketch a character’s motion over time. Once the keyframes were determined, an in-between artist drew all the frames between the keyframes.

With Final Cut Pro, you can set parameters to specific values at specific times (represented by keyframes) and Final Cut Pro acts as an automatic, real-time in-between artist, calculating all the values between your keyframes. For example, to animate a parameter, such as a rotation or scale setting, you need to create at least two keyframes in the clip. Final Cut Pro figures out the setting’s value between the keyframes, creating a smooth motion as the setting changes.