How dose the symbiote origin work?

so im planning out a symbiote character, but im confused on how it works. Lets say i use the symbiote, is it sort of like going into a form until i choose to go out of it? (like how hulk is bruce banner but when he neters combat, he becomes the hulk?)

It depends on how you want to play the character. If you would like to change into a symbiote only during combat then you can take the Alternate Form tag.