Please help me in troke swimming. I now can swim but Iam not able to swim for a longer distance?

Iam yet to refine my breathing technique and because of this Iam hesitant about swimming in the deeper side of the pool (12 feet). I now can swim comfortable in the 4-5 feet. I feel it is more fear than anything else. HOw can I conquer my fear and proceed further. Also please guide me in the best way to breathe as I find myself gulping water when I try to bring my head outside the water