I have had my Macbook Pro for 5-6 years now and really never deleted a file. Recently I tried to download a new program but couldent do it because I have to little memory, I checked and I had 908MB out of 63GB. As almost all of the files are useless to me,
I decided to delete all the files and redownload the programs/files I need.
I tried for myself but it ended with a visit to applestore to fix my Mac
so how do I do it?
I debated how to answer this, but I think the best advice I can offer is, you don't.
Your question is very similar to "I drove this car for 5 years without doing or learning anything about how to maintain it, then decided one day to start removing parts I didn't think I needed."
You either need to devote the time to learning the basics of how to maintain, repair and operate your Mac, or have someone else do it for you. Since you haven't felt inclined in 5 years to do this you probably aren't of the personality or temperment to truly want to do it now, so why bother.
I would reccomend you put in your budget to upgrade or replace your MacBook every two or three years and go on with enjoying your Mac. When you run out of space or resources you can have a new hard drive installed or replace the system altogether.