My problem about writing a technical/research report/paper
I suspect you are finding this difficult because you are trying to write in an academic style, and are judging yourself as you are writing. I think the secret to easier writing is to spend as little time as possible "writing". Instead, spend your time jotting quick emails and editing stuff. Let me explain what I mean.


Get together with someone who knows nothing about your research, and explain it to them. Record yourself, or at least take notes on the main points that you address.
Now write your explanation down, but informally, as if you were writing an email to a friend. Better yet, make it a real email -- that will help you keep it informal.
Also gather any other emails you've written to your supervisor, or colleagues and friends. (If you're not already doing so, get into the habit of writing those emails regularly, while ideas are fresh in your mind.)
Take those emails, and paste them into an empty document. This will be the starting point of your paper.
Now rearrange the information as needed, to make it coherent. Everywhere there's a gap, stick in a message like NEED TO EXPLAIN X HERE.
At this point, you're beginning to have an idea of the structure of the paper. This would be a good time to write an outline, to see if you've left anything out. This outline goes into the document along with everything else. (You can delete it before submitting the paper.)
Now fill in the gaps. But write informally, as if you were writing an email to a friend.
Now go through your document, and make the sentences more formal. Don't overdo it, though. You don't want your writing to be stilted; you want it to sound natural.


Congratulations. You have the first draft of your paper, and you barely did any real "writing"; it was mostly just writing emails and editing. 

It's much easier to make informal, but clear, writing more formal, than it is to make formal writing more clear!