You really have to stop this jumping to another thread because you don't like the answers you are getting, ask for more help in the same thread. The answers won't be any different just because you ask them in a different thread.
When you jump out of a thread the history of the problem is lost the people who have been helping you have effectively wasted their time, do you think they will come to your assistance so readily next time? Those who come to your aid elsewhere are likely to have to ask questions that have been asked and answered in the original thread, wasted effort.
OK lets try to get you started.
You double click on the hijackthis.zip file that you want to open, because you have installed 7zip, it should be associated with archive files (.zip, compressed files, etc.), 7zip will automatically be run and open the .zip file that you double clicked showing the contents of the .zip file.
1. Click the Extract icon.
2. Click on the browse icon the button with the ....
3. Click the Make New Folder or select the folder you created earlier.
- You need to extract the contents to a folder, you can either have created it first or use the Make New Folder, say C:\Program Files\HiJackThis would be fine.
4. once you have the new folder HiJackThis selected, click OK until the contents are extracted.
You should now be able to run HiJackThis.exe which will be in your new folder C:\Program Files\HiJackThis\hijackthis.exe