There is no standard "amount" of muscle that is ideal for everyone. You really just have to gauge how you feel and look yourself. Don't worry too much about accidentally becoming too muscular. It's like accidentally becoming a doctor. You have to work pretty hard at it to be absurdly big.
As you gain some muscle your body composition will change and getting lean will be easier, but theres no specific level where this happens. It's a process. Theres really no way to measure muscle amount other than by weight and body fat % (which will also give you your lean body mass %) so use the mirror or measuring tape until you get to where you'd like to be. Sticking to really basic exercises like presses, flyes, pullups, rows, squats and lunges with a weight that you can perform 3 sets of 10-12 reps, you will be able to tone and build a little muscle, but won't really gain a lot that way. Certainly no real bulk. It's an easy, basic fitness plan. Just make sure you hit all your muscle groups at least once a week and allow 24-48 hours between workouts for the same muscle group.