If you need to paste from MS Word you'll need to strip some of it's non-standard code out in order to prevent any problems which may occur. To do this when you're editing or creating a page you need to click the line which says Switch to Advanced Editor which will make the toolbar appear which looks like this...

 

 

The 7th icon on the top row is called Paste from Word.

If you have a bunch of text you've created in Word that you want to use, you should open it in Word, select the text you want to use and Copy it, then click into the web page where you want this text to appear and click the Paste from Word icon. This will open a new window which invites you to paste your Word text into it. Paste it in and click OK, and your text will be inserted into the web page without any unneccesary code.

 

This all sounds a bit tricky at first, though if you try it out, you'll find it's not that complicated and it's well worth the effort.