Ahhhh... now I see what you are referring to.
First off, you are missing 2 screws (and a long clip) to hold the bumper skin in place behind the side marker. Your bumper was probably replaced or at least removed for respray or some maintenance. Not a big deal at all as long as paint matches well. These low front ends take lots of abuse from road use.
Anyhow, in refitting, they didn't replace the screws behind the side marker light... one goes vertical (accessed behind the wheel well liner, the other horizontal... accessed when side marker light is removed - you can see the blank holes.. one for each in your two pictures. I suspect that's because the long clip behind them is also missing.
Screws I am speaking about are: #14, #15, and #16 (and #13, the clip behind, which they affix to)
Once those are in holding the bumper skin tight, your side marker light will clip into place no problem... again, #13 is needed to keep in place (yours appears to be missing but maybe not... can't see very well in the pix). Here's more info to see how it assembles from the parts diagram and parts listing (but check w/ Sunset, Suncoast, or Sonnen also for prices):
Porsche Boxster Bumper Front Parts
As well, here's a link w/ details on how to remove the front bumper so you can see where all the screws are... or should be. It's a very easy DIY so don't be intimidated (some screws used in yours may be torx or bolts and not necessarily as listed in the DIY b/c Porsche did change them based on MY).
Accessing the Radiators
Good luck
