Potty Frustration

So this potty training is really frustrating! Boys (or my boy) are really hard. I don't know whether to be angry with him at times or praise him.

For example:
On this particular day he was wearing underwear so I was asking him about every 5 minutes if he needed to go and he was doing ok. But then I saw him walking down the hall with a Barbie toilet. He walked into the bathroom and emptied it into the "real" toilet. I noticed his underwear was now on backwards too. Yes he went pee in the toy toilet. How do I explain that is wrong?

Then...on this same day...he actually went by himself to go to the bathroom but couldn't open the door because, for whatever reason, it was locked. So he opened the door to the garage and that's wear I found him with his pants down standing at the top of the stairs peeing!

He obviously knows what he is supposed to do but usually won't go unless I force him. Oh I hope this doesn't last forever!