[This assumes you are talking about entering dividends to get the foreign tax credit. If not, for example if you have dividends from foreign sources not reported on box 2 of a k-1, or didn't get a k-1, please ask again with more details.]
First you enter the Foreign taxes paid in box 14 code B (as shown on your 1041 K-1).
If you have done that, right after you are done with box 14 you will get a screen asking you about where the dividends came from. There you will enter the country (usually RIC (regulated investment company) if the trustee's statement says it is from mutual funds). Then you enter the total income from the trust, the US income, and the foreign income. The trustee must at least tell you your share ("sourced at beneficiary level") of the trust's foreign income. The total income is usually listed in box 14 code E (net investment income). That should be the sum of the other boxes for a trust that only has investment income (e.g. does not run a business like a farm or something). The US income is simply the total income minus the foreign income.
You can also take a look at this previous answer to see if it helps you.
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