Welcome Yandel! You can learn a lot from this amazing community. Nothing good happens fast in a reef tank.
To really help you, we will really need to know more specifics, like the last two posters mentioned. To help you with the type of information we need I put a list together for you. Just keep in mind, you have to be flexible, what works for me, may not work for you.
Total water volume and type of salt.
Type of Lighting and photoperiod.
Tested Water Parameters: Everything from ammonia, nitrites and nitrates, to Calcium, Mag, pH, Alk, and Salinity.
mechanical filtration, ie Skimmer, Hang on Back etc
chemical filtration, ie Activated Carbon and/or GFO etc.
How long has the tank been set up?
Many of us have lots of experience and can help identify problems just by answering the most simple questions.