How do I do a visual landing?

At the main FSX screen where I am editing my flight planner, I chose my departure airport and my destination one. After that, do I use VFR Rules or IFR Rules?

Also, I tried landing at Madeira but the tower never told me to descend or whatever so I just flew over the airport.

Another thing, when I selected VFR, when I was still at the gate, I requested clearance to depart straight out because it didn't give me any other option.

How do I know what altitude to fly at? - Very confusing stuff

If anyone could give me a basic guide on how to do a visual flight, I'd appreciate it!

From both quantity and quality of questions it can be seen easily you're a beginner. Nothing to be ashamed of, mind you. Each and every one of us has been one, at one time.

FS(2002-2004-X) have a default integrated ATC that does not follow the standards of the real life ones, especially regarding VFR. I abandoned ship desperately tired of the holes in realism no one at M$ wanted to fill a lot of time ago, giving myself to self-regulated flights and IVAO. Cannot help you with the default Artificial Idiocy M$ has supplied FS.

What I can suggest you as a beginner, is that it'd be wise you followed the flying lessons of the sim before attempting to fly on your own. They hold the answer to most of your questions and reveal you a lot of tricks, with the lunatics in the virtual tower too.

TopCat, have you flown any of the tutorials yet in FSX? Your basic questions have answers there as well as tons of websites.

For the most part, the altitude it selected by you based on proper flight planning and how far you are going and in what type of aircraft. Do you want to save gas, fly over a mtn range, take advantage of a tailwind? In the US above 3000' AGL we use the semi-hemispherical rule of eastbound (0-179) use odd altitudes and westbound(180-359) use even for IFR, add 500' for VFR ( ex: 090 hdg and 5,500' eastbound VFR).

Per your screen name, I'm guessing you are flying the 747. In that case you should file IFR above 18,000' into the flight levels.

If you stay on the IFR flight plan until your destination, FS ATC will guide you for the selected approach, if the airfield is in VFR conditions you will have an option to request a "visual" approach to the active runway. FS ATC is not the best nor accurate, but it works for the most part.