8102524LA4S iPhone

I'm not sure what you mean, but here are the steps I recommend:

1.  Make sure your iPhone is authorized on the computer you want to synch with (your iPhone's Apple ID has been authorized on the computer you're using).  If not, go to Store --> Authorize This Computer in iTunes.

2.  Plug your iPhone into that computer.

3.  If the synch doesn't start by itself, click the "Sync" button.