Using ser and estar correctly is one of the hardest things for an English speaker to get right in Spanish. Even pretty fluent speakers of the language can get it wrong now and again if Spanish is not their first language. Generally, 'ser' is used for permanent or long term things, whilst 'estar' is used for more transient things.
soy alto = I am tall
soy inglés = I am English
because if I am these things today, I was yesterday, will be tomorrow and probably will be in ten years time. On the other hand
estoy cansado = I am tired
estoy feliz = I am happy
Because these are things I am right now, not necessarily at another time.
For saying where someone or something is, 'estar' is always used, even for pretty permanent locations like cities.
Estoy en Londres = I am in London
Londres está en Inglaterra = London is in England
Soy de Manchester = I am from Manchester
So 'ser' is used with 'from a place' and 'estar' with 'in a place'.
Finally for today, the choice of which verb is used can change the meaning of the adjective it is used with.
Estoy aburrido = I am bored
Soy aburrido = I am boring
Está listo = He is ready
Es listo = He is smart/clever