Well press the Tab key on your keyboard, a screen will pop out and you will see that there is a button you can click to set it to either continuous or step mode. If set to step mode each touch of a jog key will move the amount in the DRO above, you can set that amount by pressing the Cycle Jog Step button or you click on the DRO, type the size you want then press the enter on your keyboard.
Also as RC has said you can type G Code lines into the MDI line so if you were at X 2 and wanted to go to X4 you would type G0X4 in the MDI line and press enter.
Hood