You are right: higher reps of a lighter weight will tone your muscles, while lower reps of a higher weight will add mass.

You should strive to maintain correct form whether it's a high or low rep count. To do this start at a lower weight to begin with and through the course of three or four 'sets', try to find you ceiling, or limit while maintaining correct form.

Maintaining correct form means you're working the intended target muscles, and therefor, going to get a nice 'burn' going during training, which in turn, will give you that ache the next day, and maybe even the day after that. Try to work through this 'ache' the best you can but don't overdo it. If you're just starting out you don't want to injure yourself so if you're still really sore after a days rest start with lighter weights than before. If you're at a local gym and other people are around don't worry that they may notice you lifting lighter weight or whatever, everyone's on a different program and most are only paying attention to themselves in that setting anyways.

You should train every second day if you're doing a full body workout. Your muscles need a good 24 hours to recover (48 to fully recover). 3 times a week is a good number of days for a muscle group.

If you keep this up for 3-4 weeks you'll notice you become less and less sore after work outs, and that you have to up the weights and push yourself harder to feel that burn again... this is good. This is when growth and toning starts to happen.

T1210,
DMB knows his stuff, so i will only add another nuance:

if you're after the bruce-lee build--sure lighter reps
if you're after power, which is often synonamous with speed for it's ability
to blast--don't be afraid of heavy lifting, but learn how to do it safely.
heavier you go, you may hit a muscle group once or twice in a week,
otherwise the 3 day thingy sounds great. also i've found less nonsense
and greater gains from lifts that engage greater muscle groups:
1. bench
2. squats
3. deadlifts
4. incline bench
5. chin-ups/pull-ups
6. dips [weight can be added for gains but watch how your shoulders are dealing with this]
7. loads and loads of sit-ups for tension on your stomach to compensate from all the tension
you'll be putting on your lower back.

etc...
if lifting heavy...think of a light warm up set, several build up sets, and several at a heavier weight
maintaining a 5 to 8 rep range. the easiest way to split it up is lower body twice a week, upper body
twice a week--unless you get all geeky into it, etc....which is fun but takes time and planning.

don't be afraid of heavy lifting--for injury yes, but not for what it will do for your power and speed.
don't believe the hype. i was my most power and explosive when i did the kinds of lifts listed above.

i just happen to believe it's not entirely necessary if you are starting to get injuries and such. now i let the pads dictate my limits for power and speed--and i'm doing well enough that if i'd known years ago
i would have just gone this route and not bothered with the weights at all. something really satisfying about looking slightly more average but hitting like a bull. pads/bags/makiwara...if you train right, can subject your body to the kinds of pressure not unlike weights. i wouldn't trade in a pad work out for a weights one ever...EVER!

okay, now i'm sounding like a fundamentalist pugilist, so i'll back off--DO IT NOW...just kidding