Measure your current levels, use poolcalculator.com to get everything in balance. Be sure to fill in the yellow section marked Suggested Goal Levels near the bottom. troublefreepool.com, bleach, vinyl.
If this is 100% fresh water (I'm sure it is!) you can use floaters with trichlor tablets to chlorinate while you bring your CYA up with those same tablets, or you can do everything separate. Just use the calculator to tell you how each tablet will affect the CYA as you use them. If is easier to most to keep it all separate, as in add bleach and CYA/stabilizer separately, you can do that; it just depends on what is easier for you.