One can only type in those fields that have some values already entered!
Change (if necessary) start and final epochs (from year 1000 to 3000), enter equatorial coordinates α1, δ1 into appropriate fields (for the start epoch only) and hit "CALCULATE" button. If the epochs are equal to each other, the final epoch is automatically set to the value of start epoch plus 10 years. Before the next calculation press "CLEAR".
"-" sign for δ should be marked in a special field before o window. The sign can also be entered in the o field itself but in case of -1o < δ < 0o the value in this field equals to "0" and sign will be lost.