I don't have time for a fully reply right now, but in general you need to identify all the "controls" in the form that you want to manipulate or read the values from. The basic structure would look something like: "UserForm1.Frame1.TextBox1.ActionYouWant". You can give all the controls custom names to make this easier and also if you put in the "." and start to type the name a drop down box should appear with all the possible options, which is helpful.
In terms of actions, if you only want to have something when a checkbox is checked then a good action is .Enabled. For example: "UserForm1.Frame1.TextBox1.Enabled = False" would make it so the user could not input anything into the text box when the userform is shown. This is a simple toggle of True/False.
Also to get the Value of a text box it is simply: "ValueYouWant = UserForm1.Frame1.TextBox1.Value"
With these actions and a little math, I would think that the coding you want should not be very difficult. You simply need to make it so it is triggered with a click of the checkbox you referenced and likely want to put it all in a conditional "if" statement to run if the checkbox value is TRUE.