Problem with cutting two pieces perfectly. (Beginner)

[chrisboeingr]

Hello, im very new to CAD and made my first project today. 

Now i have the problem, that i dont know how to properly align the backrest in the corner. Both are coming in an angle and one should go like in front and the other one all the way trough. I tried it out with construction layers but could not snap anything in the sketching mode. 

[jhackney1972]

Please attach your model so the Forum users can use it to show solutions to your problem. 

If you do not know how to attach your Fusion 360 model follow these easy steps. Open the model in Fusion 360, select the File menu, then Export and save as a F3D or F3Z file to your hard drive. Then use the Attachments section, of a forum post, to attach it.

[davebYYPCU · Accepted solution]

Modify > Split Body.  Cut the low grey one with the front face of the bone coloured one.

Remove the offcut.

You can fix yellow icons, with the Undo command, as soon as they turn up.

Might help…..