I know how to do header and footer but I can't figure out how to put the attorney address sideways in the left margin.

Use a borderless text box, also in the header although not in the header area. Set the wrapping to tight.

Letterhead Textboxes and Styles Tutorial
You can also use a textbox to place the attorney name and address in the margin on pleadings.

Thank you.

Now, however, the printer won't print the edge of the page. When I go to print preview, that part is cut off. How do I adjust the print margins to print the entire page without messing up my page margins?

Look at the tutorial. You cannot change the printable area on your printer without changing printers (or at least printer drivers).

Move your text box to the right. Part of the text box may be inside the left margin (indent). Wrapping on the textbox will move text on that page to the right.