How do you allocate more memory to minecraft?

I've been trying to play in the Hunger Games servers, but it kicks me out automatically saying Minecraft has run out of memory. I've got 4GB of RAM in my Dell computer. I've tried altering the runtime parameters for Java, but I might be getting the spelling wrong. I've also tried allocating it through a notepad bat file or something.
I'm not very tech savvy, but I'd like to be able to play in these servers, please :) A step by step thing would be great and highly appreciated! Thanks guys!

Ansver:

This was helpful for me, hope it helps you too:

http://www.damnthoseproblems.com/?p=186

a step by step article on how to go about things. Just select the text and right click to copy, right click in the text document and paste - that way you don't have to worry about spelling. Some chip sets and cards can just be quirky however; my nVidia card for example just seems to hate Minecraft and will randomly crash the game.

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If you're on Windows XP:
(1) Open up the START menu, then right click on "My Computer", and select "Properties". A new window called "System Properties" will come up .(This comes in handy later!)

(2) Open up the START menu, then select "Control Panel".

(3) Open up "Java". If you are in Category View, select "Switch to Classic View" in the the Control
Panel tab (Top-Left hand corner of window, under "Back/Forward" buttons". You should now be able to select "Java". Just type "java" in your keyboard, and it will select the file.

(4) In the just-opened window, select the "Java" tab at the top, and then select "View..."

(5) Now check your System Properties file that you have opened up earlier. Check how much RAM your system has. For example, you don't want to assign 4Gb of RAM to Java, if you only have 8Gb on your computer.

(6) Open again your Java Control Panel. Now, if you only have 2Gb of RAM (and below), copy this code "-Xmx256m" and paste it into the Runtime Parameters of your newest Java version, and change the numbers to however many Megabytes of RAM you want Java to use.
However, if you have more than that, say, 3GB, copy this code: "-Xmx1024m" and do the same as above. Keep in mind, that 1024 Megabytes(Mb) are 1Gigabyte(Gb)



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If you're running Minecraft on a different machine, please update your problem description, and I'll tell you what the technique is. Do this:

Edit: My system is XXXXXXXX XX XXXX (X's are in a random order, not to be confused with covering a system name)
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MY EDIT: Also, be sure to remove all your non-up-to-date versions of Java. For example if in the runtime you have 1.2, 3.5, 6, 7 then remove 1.2, 3.5 and 6.

Alternitavely, you can also paste the line of code into ALL your version runtime parameters.