I've made a video that covers the whole general process of making armour from foam. I think that watching someone else build armour is a great way to learn how to do it yourself. Here's that video:
[MEDIA=youtube]84Uc6JPxidw[/MEDIA]
Now you've also mentioned that you want the suit done by April. While it isn't impossible to build a suit in a few months, it is very difficult especially as a beginner. Take for example, myself, who has built armour before. It took my about four months to build my current suit of armour and that was with me working on it nearly every day for a few hours. Typically suits take longer than that, maybe 6 months to a year and a half, simply because making Spartan armour along with keeping up with regular life responsibilities is a delicate balance. To make sure you set yourself up for success, don't be discouraged if you have to work on the suit well past April of this year.