Hello,

When you want to fly an ILS, first you have to make sure you tuned the ILS frequency on the FMC (CDU) by selecting the STAR for your airport and the runway you want to land on. Make sure it's the active flight plan. Or put it in maually in the radio/NAV 1 panel.

When you are withing range of the airport, I guess 15 nm or whatever, press the LOC button on the MCP. Then the AP will track the localizer signal from the runway. When you are close enough you should see the G/S become active on the right, (I usually intercept from below) then press the APP mode selector. The plane will then fly the ILS and the 3 AP selectors will automatically light up (it takes the 3 computers to do an autoland).