What problem are you having exactly? do you not know how to start to wire it or what? You need to be more specific...
However, assuming that's the case, you need to ask yourself what you want to use the ampeg head for. I recommend only using the B2R as a power amp (hopefully it can try and be decent at that).
In order to hook this up, you'll need 2 instrument cables and a speaker cable (I assume you have the speaker cable, to hook up your B2R to the cab). So in order to bypass the preamp section of the B2R, which you definitely want to do, you will take an instrument cable and look on the back of your Sansamp for a boxed-off in white border section that says "Output" and plug one end of the cable into the jack that says "sansamp". After you've done that, plug the other end into the jack on the back of the Ampeg B2R that will say something like "effects return" or "effects loop return". This skips the preamp of the ampeg so you only amplify the wonderful Sansamp tone. After you've done this, just connect the ampeg to the cab the way you regularly do, plug your bass into the front of the sansamp and you are good to go!
** To hook the tuner up, there should be able to use a regular instrument cable and plug it into the "unaffected" jack (right next to the "sansamp out" that you used to connect the sansamp to the Ampeg head) and just run that to the tuner. Haven't tried that before but it should work ok.
Hope that helped! =)