Jarl Ulfric

I asked him to come and talk about trade. He agreed.

I then stated that he should make a open trade agreement for free trade.

As a sign of friendship

He agreed.

The details are

Food

Weapons And armour

Spells

Magical related items

And more

In exchange

I will agree to the Imperial to not follow the laws of the empire but new laws Skyrim.

Meaning empire will be here but the laws of the empire will not be laws here only if it's agreed-upon in Skyrim by appointed authorities/jarls.