Shopify does not provide a WYSIWYG editor for editing things like product descriptions. Instead it uses something called "textile", which is actually very powerful, however it isn't that intuitive for new users who are not technical. We often have clients asking us if there is an easier way to edit things. Well sure enough, there is a way!
The trick lies in using an open source WYSIWYG HTML editor called "Xinha" (yes, it is pronouced the same as the TV show Xena), and a FireFox Plugin. If you haven't got FireFox I highly recommend it as it is secure, supports standards better and is faster (download it here).
Once you have it installed, you can now right click in the product description area and you will see a new menu appear "Open Xinha Here!". Click that and now you have a nice friendly editor to enter product descriptions (or write blog entries in).
You can do a lot in Xinha visually, including creating HTML forms and tables.This can cause conflicts with Textile, so you should disable it by putting <notextile> and </notextile> around the text after you have finished editing.