Conversations about disagreements are hard in any language! Here are some useful English phrases to help...
1) I see things differently.
2) I am on the opposite side of the debate.
3) Our opinions diverge.
4) I beg to differ.
5) And finally, if there's no chance of agreement, this phrase can help stop a long argument:
Thanks for your opinion, but we will have to agree to disagree.
If you want to be less direct, you may agree about something first, before moving on to make your point:
Now it's your turn to disagree!