For this my writing exercise I took some jokes in Russian and translated them.

You can say "this" or "my" and it will still be correct. Using both words sounds a little strange.

Please tell me haveif I managed to keep them funny?

In the director's cut of "Harry Potter" all wthe only thing that happened withto him is a mess in his head after he hits it on the wall in King's Cross Station.

But all what they did is kicked himer out from the cinema.

"Granny" is usually used for grandmas. Is this your grandpa or grandma?

While Stephen King was explaining to a traffic police officer why he was speeding, he peed twice and turned grey.

Please tell me, have I managed to keep them funny?

In the director's cut of "Harry Potter," all weverything that happened withs to him is a mess in his head after he hits it on the wall inat King's Cross Station.

I think I get this one, but I'm not sure why it's the director's cut :)

My granny shouted very loudly and tryied to warned everyone on the Titanic that there is an iceberg right ahead.

But all what they did iwas kicked him her out out ofrom the cinema.

This is very funny, but remember that him - male and her - female!

While Stephen King was explaining to a traffic police officercop why he was speeding, he peed twice and turned grey.

I'm afraid I don't understand this one.

For this my writing exercise I took some jokes in Russian and translated them.

The "this" is not technically wrong, but the sentence sounds more natural without it.

PleaseCan you tell me if I have I managed to keep them funny?

Again, the original is technically correct, but reads a little stilted. Using "Can" keeps the tone polite, though you could add please at either the beginning or the end to be very polite.

In the director's cut of "Harry Potter" all weverything that happened withto him is a mess in his headthe hallucinations after he hits ithis head on the wall in King's Cross Station.

Either "what" or "all that" would be correct, but "everything" sounds more natural. "all what" is definitely not correct. "A mess in his head" is understandable, but not what anyone would say unless they were being super casual. Hallucinations are neurological - in the head - as part of their definition, so there's no need to specify head with it.

My granny shouted very loudly and tryied to warned everyone on the Titanic that there iwas an iceberg right ahead.

Past tense is never applied in the "to" form, so it goes with "try"-"tried". So "tried to warn", not "try to warned". The whole sentence is past tense, so "was" instead of "is".

But all wthat they did iwas kicked him her out ofrom the cinema.

Definitely "that" instead of "what", though I couldn't tell you specifically why. "Was" for the past tense here, rather than applying it to "kick". "Her" since "granny" is female. Unless it's your grandfather, in which case it would be "grandpa" and "him".