Check this site for some help on how to take measurements with your dial indicator. It's geared at a particular alignment measurements system, but you will get a good idea of how to use yours from readaing what it there.
Or try this site (copied from a post I made in another thread)
This video (below) will show you how to determine if the problem is your blade or arbor:
You can download from this page also, right click on the link where it says
" Instead, use this link: Table Saw Alignment "
and choose "Save As" to save the video to your computer hard drive.
But beware, it is 48 MB (don't even think about it on dial-up).