How Can I Get Into IB Classes ?

Well , I Was In 7th Grade , Now Going On To 8th , and I Am Thinking About What High School To Go To . I Want To Go To John F . Kennedy , But People Say It's A Bad School . They Have IB , AP , and Honors Classes , And I Wanted To Know How I Could Get In IB Classes . I Have Had Straight A's and B's Since 1st or 2nd Grade , But I Sucked At Math , So I Had To Take A Extra Math Class This Year Called Aleks . I Got Out Of It Though . But Anyways , Can I Get Into IB Classes , and If So , How ?