please tell me how to say these in english?

You could say

-I am seeking a long-term job with the opportunity to improve my position over time and with the right credentials.

or something like

-I would like permanent employment that offers status and wage increase.

-I would enjoy having a career job including status improvement availability.

Its getting there but say this more formal I.e.

i want the company to offer me the opportunity to get greater position and stuff

Instead you could say: This company would give me the opportunity.. Not only to succeed well in my job, but giving me a higher position.. Etc.

Do not say stuff sounds very informal

With any job you'll be able to move up and get promoted so it'd be rude to say that in the letter. But for having a permanent job, say, "I am looking for a permanent job."

Just say "I am looking for a job that has promotion opportunities."