google return mitres, this will show you what it should look like and you tube will give you an idea on how to do it. In terms of the step you need to return the mitre around the corner and then mitre down to the floor and mitre again to continue the line of what the skirting would normally follow.

yup, exactly. here's your chance to buy a power mitre saw! watch you fingers and put safety glasses on, the small return cuts will jump off the saw. practice, practice!