Ok first i'm going to go through the most common method of uploading.
1. Manualy uploading using your personal connection. This can be done either through the http://www.rapidshare.com website or Rapid Uploader. Which ever you choose, I personaly think the Rapid Uploader is MUCH easier and makes it so much simpler and quicker for you. All I would reccomend if you dont have a rapidshare premium account I would signup for a collectors account (free but can collect points to generate premium accounts) and collect all your uploads within that. If you do have an account then you can simply enter your login details into Rapid Uploader and then they go straight to your account.
2. Using a web hosting account (leeching but for people with bad connection). If your own personal upload speed is too slow, and annoying for uploading large files. You may use a PHP web script named Rapid Leech what simply downloads files from http://www.rapidshare.com. This can be found over here at http://rapidleech.com/. The script simply uses the web servers fast connection speed to download the files to the web server (your web hosting space). You then simply login to your rapidshare account and click on "Remote Upload" and then put in the links that lead to the files Rapid Leech downloaded. So for example, I want to upload this file to my rapidshare account:
What I would do first is goto my script on the webhosting what we will have for example as rapidleech/. Then you can change your settings so that its configured with your account and then goto put in your RapidShare URL and let it download. Once it's finished it will let you know and also give you an average speed (useful for determining best times to download using Rapid Leech). You can then click on the tab named "Files" and if will bring up a file manager with all the files you have downloaded. For this example we will see "MaxGammonBackgammon.rar". Rapid Leech then has features what allows you to do things such as rename the files so its "MaxGammonBackgammon_2008.rar". After then we go ahead and login to our RapidShare account and put the link into the remote uploads. For this example we would put in rapidleech/files/MaxGammonBackgammon_2008.rar. Rapidshare will then download the file from your web server and then upload it to RapidShare.
NOTE THIS USES ALOT OF BANDWITH SO MAKE SURE YOU CHECK HOW MUCH YOU ARE GOING TO NEED!
3. Using a dedicated server. This is an expensive method but can be very effective. You could do all of the things in method #1 but on a 100mbit connection. This is the best of both as we are able to do more than just rename our files but change passwords,NFO's and the general content of it. You could rent a dedicated server for a month, do all your uploading and maximize the usage of it (make sure its allowed by your dedicated server provider first) then post up all of your uploads after.
They are the 3 main methods that I know of for uploading to RapidShare, i'm sure there are more out there! I hope this helped you discover the best ways to upload to RapidShare