how do you set margins on a typewriter?

Answer 1

Use the margin settings = metal levers and guides.

There are two levers that are behind the roller on a typewriter. You unlock the lever and move it to set your margin, on the provided scale. There will be a paper guide connected to it. Do that on both sides and you are ready to type. You can also set a Tab stop for when you are indenting paragraphs.

Answer 2

There are metal adjustment pins or clips in the back of the machine that you manually put in place; they stop the platen from going beyond that position.