Hi maz,
Plugins are used as effects (like adding reverb or compression or eq or delay) to a certain part or all of a track that you are working on with the software that you are using. You don't have to use any if you don't want to. They can just be convenient if you want more control over how your tracks sound when you try to edit the already recorded track. You can add one or more plugin effects to a track or the whole song (some software lets you use an effects send/return auxillary channel to do this so it won't use so much of the computers resources).
If you have a slower computer, just experiment as you record some tracks, then after that is done, if you want, put in a plugin or two to, say for example, one of the vocal tracks, and just see how it works on your system.
Its nice to have the editting control when working on computer recording, so you can add a plugin effect, listen to it and see if you like it or add more of it or less of it, or if it takes too much from your computer when you are playing some tracks back, just don't put it in at all. If you want, you can add effects before it goes into the computer with an effects box you might already have, I don't think that uses up your computers resources.
Hope this helps.
bobbo
