With a few steps, you can make a character walk across the screen.
By default, the character action is set to "Idle". Click on it and from the top, select the "Walk-In" action.
Click Add Action, and select the action you want the character to do after walking. In this example, we will select Wave.
Place your character to the right of the screen or canvas, that is where the character will be after walking.
Now click the add button (+) to add an Animations, and select Position.
Place the character back to the left of the canvas to mark the starting point.
On the tracks, drag the animation just about the same length of the Walk In action. If the character slides, just decrease the animation length a bit.
Right-click on the animation and select Easing.
Click Both and select Linear.
To make the character walk back to the left, right-click on the character track and select Duplicate.
Drag the duplicated character until it snaps with the last character clip.
Now, make sure to click the duplicated character track (it will turn blue) and click on "Flip Horizontally" so that the character will face to the left
And lastly, right-click on the duplicated character animation and select "Reverse"
Please note that this can be done only to characters that have the walk action.
That's it! You now have a character walking across the screen.