what? :scratch:
You don't
need constant light, except to see by...and that could be any type of light you want...a lamp, a lightbulb in a socket etc. It most likely won't affect your shots if you are using flash/strobes.
What you need are lights for your subject...1, 2, 3, 4....how every many you want or can afford etc. (It's often recommended to start with just one (or maybe two) and learn that first) These should be flash/strobe lights.
Now, there are two main types of flash/strobe lights. The first are small 'flash' units like in the kit I linked to. They run off of AA batteries which makes them very easy to take on location.
The other type is what we would call a 'studio strobe'. It runs off of AC power (needs to be plugged it).
Example
There are pros and cons to each type.
One pro of the studio lights, is that they have a 'modeling lamp'....basically they have a regular light bulb to give you constant light...which gives you a preview of the flashed shot at can also give you light to see by.
Now, with either type of light, you will probably want modifiers. These could be umbrellas, softboxes, snoots, grids etc. Something to put over the light to change it's characteristics. Although there are differences between softboxes and umbrellas, they basically do the same thing...and that is to soften the light.
If you are using flash/strobe lighting...you will need a way to trigger them. The kit I linked to, comes with a cheap radio trigger that would work. Most studio lights have a built-in optical slave, so you only need to trigger one of them from the camera, the rest will fire along with the first one.
You may also want/need a flash meter to be able to measure the flashed light...because your camera's built-in meter will not be able to do it. Although, you can get by with some trial and error if you don't have a flash meter.
As for where to put the lights, how to use them, what type of modifiers to use...that is all up to you...and for you to figure out.