I am not sure what do you mean?
A bench is a seating element. If you go to the Furnish library and search for "Bench" you will find lots of difference benches (see attached). You don't need to attach these elements to a wall.
Otherwise, try to detail the problem as specifically as possible, so we can understand the issue. Let us know exactly what you want to do, what you tried, what seems broken, etc. Or, if you can, post a picture of the desired element.