Unzip downloaded Files

I have PKWare and its ZIP Reader. From your question I inferred I may fair better with 7 zip and downloaded that too.
On the icon for downloaded 7zip Right clicked . . . popup with 'OPEN' bolded came on. Left clicked 'open' and it opened . . . installed it . . . checked and found it in 'Programs' . . . Opened the 7zip program and it showed bolded 'computer'.
Now please tell me how get about unzipping the earlier downloaded software that have icons on my screen.
Thank you very much indeed,
ben aloysius