Hi Nann,
As a beginner, your main center must lift safely with proper structure and light. When you get this right, you can start doing shift sets and reps.
Titles
For muscle strength: Complete 1-6 reps with 3-5 sets of rest somewhere close to 2-5 minutes between sets.
For Muscle Hypertrophy: Complete 7-12 reps with 3-4 sets resting somewhere close to 1-2 minutes between sets.
If you're a beginner, focus on 3 sets of 8 reps with 90 seconds of rest to boost strength and muscle gains.
When you hit these, try increasing the reps. I had seen apparent impacts within the first month.
good luck.