$$(((p\land q)\lor r)\land ((p\land q)\lor s)) \to ((p\land q)\lor (r\land s))$$
I don't know how to finish this proof by natural deduction using tree. First I used $(\to I)$ I got $((p\land q)\lor(r\land s))$ then $(\lor I)$ I got $(r\land s) \land(I)$ I got $r$ and $s$ and I finished here and don't know how to continue.
I appreciate your help.


Your $\to \ I$ rule is not applied correctly.
Indeed, instead of starting with $r$ and $s$, you should start with the antecedent of the conditional you are trying to prove, i.e. start with:
$((p\land q)\lor r)\land ((p\land q)\lor s)$
and see if you can derive
$(p\land q)\lor (r\land s)$
from that.