i am being asked to put outgoing bandwidth to 75%. how do i do that?

You can set outgoing bandwidth limit on Bandwidth View. You'll have to know what is your maximum outgoing bandwidth. Optimize Tixati help guide describes what to do. I'd use speedtest, on settings page there change Speed Measurement to kilobytes (the same unit as in Tixati bandwidth limiter), then test your speed to a few different servers near you. The best upload speed result is your maximum outgoing bandwidth, use 75% of that as your limit.