I'm guessing that your midi instrument is a software unit.
The sound of this software unit is comming out the SoundBlaster part of your computer.
If it can be Rewired for example ... you need to route the output towards Pro Tools via the Rewire plug.
Look for output options for the synth.
PT will now need an AUX input and the Rewire plug with the above Synth needs to set up on one of the inserts of the AUX input.
It will probably need a stereo input.
use some audio leads and connect the SoundBlaster output to a spare input of the 001