Steps

insert the pen drive in usb port
copy that file on desktop
open the file by double clicking it
select all the matter by pressing ctrl+A
copy it by pressing ctrl+c
now open the blog and login in it
click on the new post
type the title
now click on the text window
now press ctrl+v
text will be pasted in the text window
allign the text as per your requirement
now click on the post
publish post