i am using raspberry pi
have pca9685 servo controller
and i want to controll servo on blynk
i wired the servo controller i have it working with python but i want to use blynk
Be aware, Blynk Python support is extremely limited… you will need to do a lot of reading and testing.
? All I want to know is how to add servo controller pwm and use it with slider
…so… use the Blynk Python library and add slider code that supplies a value to your “working” Python controller. Click on the link above and read through the examples. I don’t speak Python, so the rest is up to you.
If this answer is not good enough, then perhaps clarify your question 
I’m not good at python I don’t under stand how to do that all I want to do is move servo using servo controller
It helps to know what you know, and based on your past comments, that was Python 
Again, perhaps more clarity…
So anyhow, then don’t use Python… try NodeJS… or you could even look at WiringPi that uses C++
I’m not sure what else you want here… we help you learn about Blynk, but no one is going to write your code for you.
Ok I am use raspberry pi 3 b and a pca9685 servo controller how do I use the pca9685 to controll servo I am makein a car and I am trying to controll the 2 servos
Do I have to write code
Yes… particularly for that controller.
I don’t know for sure… I don’t have one.
But generally you decide which language you want to program in, then install the Blynk library in that language, then learn some basics about how Blynk works, then write some code to take the value from a slider (or other widget) and use that value with whatever library works with that controller.
What controller can I use with this app to controll servos without adding code
None
On Arduino and ESP you can hook the servo signal wire directly to any PWM capable pin, power to an external 5v source and share the ground between that power source and the Arduino/ESP.
On the RPi I think GPIO18 is supported natively for PWM. But no guarantees that any other pins will work without first adding suitable GPIO/PWM code (not Blynk related). Google RPi, GPIO and PWM for that…