For future reference, this part of the forum is usually used for "meta" discussions about the forum. You would have gotten better/faster responses in the general discussion, ask a mustachian, or tax parts of the forum.
White Coat Investor is a great source for backdoor Roth information. He has a post walking you through every step (it may be linked to from the post you found).
It would be unwise to make non-deductible contributions to a traditional IRA with a large previously deducted balance because any Roth conversions will be mostly taxable, which isn't ideal at your current high rates. If you 401(k) accepts rollovers from IRAs and the investment options are acceptable to you then rolling the IRA into the 401(k) to allow backdoor Roth contributions with minimal taxes on the conversion is a great option.
If you IRA is a rollover IRA (from a 401(k), not from direct contributions) make sure your 401(k) provider knows that if they tell you they don't accept IRA rollovers as some plans will accept a rollover IRA even if they won't accept a contributory IRA.