Webpage in portal block

[RW076]

Good day,

I am looking for help on creating a custom portal block.
On our site (www.lmsalesportal.nl) I allready have a custom block (bottom), but now I want to display there a specific page of another site. (could be any as an example)
What is the way to create such a block?

Thanks in advance for your help, I feel like an idiot asking this question but couldn't use the search the right way to check if someone else had asked this question.

[ShocK]

Can't see anything at that URL, what about using an iframe?