zeemas gave you a nice procedure to help create openings, drawing null (property NONE) lines, then Edit menu mesh areas to mesh your walls to create openings. In case you don't already know, you select a meshed area where you want to have an opening and press Delete key on your keyboard to delete it, thereby creating an opening. Another method is to add reference planes and reference lines, then use Edit menu to mesh areas based on visible grids.
Using either zeemas' suggested procedure or reference planes & lines, if the opening is the same size and location on multiple stories, you can mesh the wall on 1 story and then replicate to other stories in order to save time
The draw windows and draw doors draw tool options look nice, but you cannot easily mesh with precision using those draw tools from what I can see