The absolute values for heart rate vary from person to person and change as you age. But I do notice that my resting heart rate slowy drops a bit as I get fitter (e.g. during a marathon build) and will rise more suddenly if I am getting sick or not getting enough rest.

I don’t really pay much attention to the heart rate zones on my watch, but I do have a pretty good idea e.g. where my 5k race vs marathon race vs really easy run heart rate lies. This can be one piece of information along with perceived effort and pace to decide if I should be able to push a bit harder on a hard run or take it a bit easier on on what is supposed to be an easy run.

Start out slow (no, slower) and don’t be afraid to take walk breaks if you need them. Try your best to get out at least a couple of times every week (but not every day) for at least half an hour or so. Progress will take time, but you will find that you will gradually be able to go farther and faster.

The cannonical texts after completing a couple of novice plans are Daniels (Daniels Running Formula) and Pfitzinger (I have Pfitzinger and Scott Avanced Marathoning but there also is Pfitzinger and Latter Faster Road Racing 5k to Half Marathon). I think these have been mentioned in other replys. These books are good to have as they give a little explanation as to why you are doing each workout in addition to the plan. Daniels just gives a couple of hard workouts a week and you fill in the other days with easy running. While the Pfitzinger plans are the usual prescibed workout (or rest) for each day. These plans don’t have as much of a ramp up as the beginner plans so you want to be used to putting in some significant mileage each week along with a hard workout or two before you start one of these plans. But other than that they are pretty accessible.

5k pace will feel like “I really want to stop now, but I can keep going if I push myself” then recovery will feel like something of a relief. Recovery pace may not be much faster than walking (try not to walk, but if you have to walk after a hard burst don’t feel bad about it). But most important for now is to get a feel for running at different speeds and intensities. Don’t kill yourself, but don’t be afraid to run pretty hard for a little bit.