I assume you have a roller furling genoa, since you said you rolled it up.
Basically... a genoa extends past the mast, a jib does not..
How much extends past the mast or how short it is to the mast is basically
what the numbers mean.
So a 100% jib goes from the forestay to the mast but does not extend past.
everything over 100% ..represents the % of the sail that extends past the mast....so a 150...is 100% and 50% more...
A 150 is a big sail....great in light airs..and for downwind sailing..
Depending on what the typical wind conditions are..where you sail, you may find yourself overpowered when headed into the wind. The problem with Big roller furlings imo...is that when you roll them up they lose their shape and efficiency. So more is not always better...sometimes a 125% is more appropriate.....it depends on the prevailing winds, the boat etc...
I went to a 130 from a 150...and am quite happy...I can fly my whole sail more often than not.
Your mainsail should have two large cringles...one at the luff (front) and one at the leech (back) of the sail....you secure these points first...
then there's probably 2 or 3 grommets in the middle of the sail in line..
Do you have any lines going to these points now?? ..is there a set of rings at the luff...? and a line in the leech? do you have any pictures?...
Do you have a loose footed mainsail...or does your mainsail foot...slide into a boom track??
here's a link....I'm sure there's more
Weather and Reefing