How long does the immigration from yemen to the us take?help me please.i need it.?

i am an iraqi teenager living in yemen and i wanna attend my high school in the us so how long does the immigration take?i am travelling with my mum.my mums qualifications is that she has a high medical certificate.she only needs to qualify it.my qualifications is that i have a british certificate that is called checkpoint.i got good marks in that examination and i am studying in the best school in yemen and my english is good.so how long does the immigration take?can i shorten the time by some qualifications?can u give me a governmental site that i can trust to give me the visa?answer all my questions please.i need it,