Purpose
This is a small tutorial for uploading and downloading from SendSpace. It's not great, but, hopefully, it will be understandable. Since most websites are typically the same, this can be adapted accordingly.

Sites
YouSendIt: Maximum file size = 1 GB
SendSpace: Maximum file size = 1.2 GB
RapidShare: Maximum file size = 100 MB
MegaUpload: Maximum file size = 250 MB
FileFront: Maximum file size = 1 GB

Uploading
Step 1: First of all, you should pick which site you want to upload to.
YSI is the most commonly used, while having a pretty good upload/download rate, it has been known to fail at times. MegaUpload is another commonly used, the upload rate is fairly decent, but the download rate is extremely slow. SendSpace is my personal favourite, the download speed can be pretty slow, but the upload speed is the fastest I've come across.

Step 2: Now that you have a site, you can start the tutorial.

First, go to the SendSpace website, you should see something like this. The first part is "Select file", click "Browse..." to select the file you wish to send. Next is "Description", this is optional. Third is "Recipient's email", again, this is optional. Last is "Your email", this is also optional, but it's recommended you enter your email to have the download link sent straight to your inbox. Click. This is useful if the person you're uploading for loses the link, or if you just want to keep track of what you've uploaded. Once that's all done, click "Upload File". You should get something like this.

When your file has been uploaded successfully, you'll be taken to the confirmation screen, containing the download link, and the deletion link. Click.

Downloading
First of all, click on the download link you were given, you should see something like this. The download should start as soon as you click the download link. If it doesn't, it just means there's too many people downloading from the website at the same time. You'll be taken to another screen with a counter of "60", as soon as that hits "0" click the link again. This very rarely happens, so you shouldn't have any problems.