Proofreading is not a huge, difficult science. Just read what you wrote and, chances are, you'll see that letters are missing from the end of words, or that you used the wrong version of 'their'.
This is especially true if you use social media as part of your business, or to give advice to others. I will not take your advice or buy your product if you are so careless about how you present it.
If you posted something this morning, go back and reread it. Trust me.