How to move the cursor to a specific position in a specific line in ScintillaNet control?

Is this what you are looking for?

SCI_GOTOLINE(int line) This removes any selection and sets the caret at the start of line number line and scrolls the view (if needed) to make it visible. The anchor position is set the same as the current position. If line is outside the lines in the document (first line is 0), the line set is the first or last.

Taken from