At the top of your guide there is a button that says 'Edit', if you click that you can edit your guide. You can also find your guide if you go to your profile (top right of the screen) and then click the button for 'Guides, Discussions & Media'. :)

Oh, quick note, bbcoding like using [ brackets does not work within notes (you can instead use them within the guides chapters, which you can also find in the editing part of the guide, in order to make things like First Strike into First Strike).