If I understand your question properly, you simply take the obstacle weight given by the data and subtract your figure from that. I've not used the type of performance page you linked - only Aerodata or APG - but it appears the first number is your take-off weight divided by 100 (followed by your V-Speeds).
So simply multiply the weight figure by 100 to get your allowable take-off weight and then subtract your performance restrictions from that...for example if you read 792 as the figure, that's 79,200 kilo for take-off subtract your 7,950 from that giving an actual allowable take-off weight of 71,250 kg (roughly 159,600 pounds). Any 737 pilot might want to clean this up if I'm in error though.
As for your question about Obstacle or Climb Limit weights...you'll have to take a performance course, but as simply and roughly as I can a Climb Limit does not take obstacle clearance into account - it means that you can take that weight off that runway and still climb (on all engines). Obstacle or Field Lengths take that obstacle clearance into account (on one engine), hence the reduced figures.
So, operationally...if you assume obstacle clearance you can take the Climb Limit weights...if you want to make sure you can climb away, use the Obstacle/Field charts...in other words, VFR/IFR.
That was horribly rough and does not do a service to all the information behind that sketch. I would suggest you Google "Flight Manual Performance" or "Pilot Guide to Takeoff Safety"...both are good starting documents.