Think about what you want to happen. A Do loop does something either While something is True or Until it is True. You can test that condition either before you Do something or after. You simply need to ask yourself these questions:

What do I want to Do?
Do I want to do it While something is True or Until something is True?
Do I need to test this condition before doing something or after?

I have to say, if you need to change a working For loop to a Do loop then this must be homework, so for us to just provide code is unethical. The fact that you're using "ui" as a prefix is more evidence of this because I've never seen anyone but students use that. Your user name kind of gives it away too. I suggest that you answer those questions for yourself and see where that leads you. Try writing some code and post back if it doesn't work.