"However when I try to select a number... J(1,6)... this displays -9.4623 when I throught it would display 9.4623"
The sixth value in the first row is -9.4623. You did not explain why you think it should be something else.
"also when i then try to select the second number ...J(2,6) ... I get the following error "
The array J has only one row: what do you expect to occur when you try to access an element from a row that does not exist?
"Does anyone have an idea how i can reference to each number within J?"
Because your data are in a vector, linear indexing is sufficient, e.g.:
J(2)
J(6)
