Gear indicator on SRAM X5 Shifter shows wrong gear
I don't know if you're still having this problem, but this could be useful for others, so I'll go ahead and answer it.

To be honest I wouldn't bother trying to fix a gear indicator, especially a front one. It's not difficult to remember which chainring you're in and opening up the shifter is definitely going to invite problems for inexperienced mechanics.

What Chris said is probably wrong: the gear indicator will not be affected by cable stretch.

The above notwithstanding, this is a very easy problem to remedy.

1) Shift the chain to the lowest chainring (least cable tension).

1.5) Slide the shifter off of the bar if possible. (This step is not strictly neccesary, but I find it makes things easier.)

2) There should be a number of small allen key heads around the top of the shifter. Undo these and carefully remove the top cover of the shifter. Take a picture of the internals in case anything falls out.

3) The top cover is composed of the cover and the bar clamp (which contains the gear indicator). All of the working parts are contained in the lower part of the shifter. In the middle of all of these you will see a cog which is raised up and doesn't appear to mesh with anything. This is what drives the indicator. On the underside of the top cover you will see a toothed strip of plastic: this is the indicator. Slide it with your finger to '1' (which is where you should have shifted to at the start).

4) Put the top cover back on and put the shifter back on the bar.