I need a more upright position... I have a threadless headset and don't understand stem angles. As in, 84 degrees, -5 degrees ect... Could someone please explain this so I can buy the right stem. Thanks

Briefly, a 90 degree stem is perpendicular to the steering tube. MTB users call this a zero rise stem. A -6 degree would be the same as an 84 degree. Flip an 84 degree and you get a +6 or 96 degree angle. A -10 is the same as an 80 degree. Flip an 80 degree (-10) and you get a 100 degree or +10.

The lowest angle is a -17 or 73 degree that is horizontal to the ground. An 80 degree will raise the bars about 1.3cm. An 84 will raise the bars about another .8cm or 2.1cm in total. A 90 degree will raise the bars another 1.1cm or 3.2cm in total. A 96 degree will raise the bars another 1.1cm or a total of 4.3cm. A 100 degree will raise the bars another.7cm or 5cm in total. All of the above values are for a 110mm length. Shorter stems will have a bit less rise and longer ones a bit more.