If you just want to be able to read Word documents, you can download the
Word Viewer from Microsoft. This lets you read those files even if you don't have MS Office installed.
If you're looking for Word or the whole Office suite to install, you'll need to buy a copy. There isn't any way to legally obtain a copy you know will install, activate and run correctly unless you pay Microsoft for it. There is a free alternative, though.
OpenOffice is 100% free to download and install, and it's a complete office suite with all the features of MS Office. It can read and write Word docx format files as well as many other formats. Why not look into it?