Fix an old todo in the docs (#1981)

This new paragraph might not be great and it certainly is less
informative than what the wiki said here (it suggested to use some
library for widgets and explained how to use it). However, this new
paragraph is definitely better than the todo that was here for far too
long.

Signed-off-by: Uli Schlachter <psychon@znc.in>

docs/07-my-first-awesome.md

@@ -171,7 +171,28 @@ A new window will appear and a new awesome instance runs inside of it.
 
 ## Add widgets
 
-TODO: Write this section.
+Before the following line:
+
+    mylauncher = awful.widget.launcher({ image = beautiful.awesome_icon,
+
+Add this to create a new widget:
+
+    praisewidget = wibox.widget.textbox()
+    praisewidget.text = "You are great!"
+
+The widget still needs to be added to a wibar. For this, find the definition of
+your wibar and change it as follows:
+
+    { -- Left widgets
+        layout = wibox.layout.fixed.horizontal,
+        mylauncher,
+        praisewidget, -- This line is new
+        s.mytaglist,
+        s.mypromptbox,
+    },
+
+This gives you a basic idea on how to add a widget. For an overview of available
+widgets and how to arrange them, please read @{03-declarative-layout.md}.
 
 ## Further reading