Write the Context free Grammar
Your grammars for $A_1$ and $A_2$ seem correct. Since you want to compute the concatenation of $A_1$ and $A_2$, you just need to express this fact with the start symbols of $A_1$ and $A_2$.
$S \rightarrow S_1S_2$ is a way to do it.
You can check by computing the derivation that creates the word $001110$.