After you zero the indicator needle, it's usually a good idea to check the calibration.
- Clamp square-drive in vise with wrench-arm perfectly horizontal, might need to use some V-blocks if your wrench's square-drive is 45-degrees off
- using a strong rope/cable, hang a weight of around 25% of wrench's max capacity from handle (use precision scale to measure this weight, such as calibrated scale at the Post Office or UPS office. Bathroom scale isn't accurate enough).
- length = measure distance from centre of square-drive to hanging-cable in inches
- calculated torque = weight * (length /12)
- read off torque indicated by wrench, how closely does it match calculated torque value in previous step?
Check this
Park Tool - Torque specifications page for a list of common torque-settings on bikes. The highest torque you'll typically use is around 30 lb*ft for the crankarm-bolts and cassette-lockring.
Your wrench is way too big and inaccurate for the ranges used on bikes. Heck, it's a bit much for cars unless you regularly install cylinder-heads. You may want to get something in the 0-400 in*lb range (0-33 lb*ft) to work on bikes with higher resolution and accuracy.