SLM, welcome back to marijuana. If you haven't smoked in 30 years, you can probably hold off on the joints for now especially if you already have a bowl. When you are ready for joint rolling, you can use google for some advice like Matt said or use the search feature on this website to find threads on how to roll a joint.

How much pot you need to smoke depends on how good the pot is. Luckily, you really can't mess this up if you have a bowl. Break up a small amount of pot, probably less than a gram, and pack some in the bowl. Take a hit or two and then wait a few minutes for the effects to hit you. If you aren't getting the effect you want, smoke a couple more hits, then wait. You probably should start by treating your pain "as needed" then when you get used to the effects of the pot and how long it treats your pain, you will learn to time your smoking better because for many it the pot will work better if you smoke before the pain surfaces than smoking after the pain surfaces.