Hey Boyan,
So, in order to calculate the risk per trade and to make it be 1% per trade, you can try this link:
https://www.babypips.com/tools/position-size-calculator
It will help you calculate the risk per trade for the pairs that you wish to trade. I know that you said it’s portfolio but you can just see what pairs you have chosen and depending on that, you can write the correct information in the link that I provided so that you can see what would be the lots size.
Also, regarding the news filter, I suggest that you have it on, especially in a challenge!
Hope this helps!
If you have any more questions, let me know!
Kind Regards,
Nikos