Goog math site for 7th grader. also how can i skip a grade.?

i need some free websites mostly for math wich i am at a 5-6grade level and im in 7th grade. i am at a college reading level. i want to skip the 8th grade and go into highschool so i know i need to study both 789th grade levels. please no comments like its hard skipping grades abd i shouldnt do it blah blah.