To convert your document to a PDF, go to File > Save As > and there should be a PDF option under file types. You can also go to File > Print > Print to PDF.
There are many PDF conversion and size reduction (file compression) websites – so Google “Convert document to PDF” or “PDF compress” to see a list of websites.
If you have Adobe or Preview, you can try on those tools: Using Adobe it should be under Document > Reduce File Size. In Preview (on Apple computers) open the PDF go to File > Export > there is a dropdown at the bottom of the screen that says “Quartz Filter” select the “Reduce File Size” option.