There is a blinking vertical line at the space

There is a blinking vertical line at the space where I am typing now. I made the mistake of moving a bar and now this bar is too wide. Please help me get back to where I can change the setting and make it thin again. The letter being typed will go under the bar and if I delete, it removes the letter that is left of the bar. The bar is about 1/8th of an inch wide. It used to be about the width of the letter capital ''I''.
Alice Voysey
amv@gforcecable.com