I recently made a really good electro mix and I want to know how I can shrink it(MP3) and then e-mail it to a friend... Any suggestions??

During your conversion to mp3 select a lower bit rate.

You can use Cool Edit (http://www.adobe.com/special/products/audition/syntrillium.html) to do the conversion

Totally confused, I just want to put my mix or another mix onto a site so I can upload it to the itunes store for others to peep out. "Podcast" I tried a few programs and nothing seems to work for me. What is the solution, I know it's not that hard, but I am running into a brick wall.

You can't upload it to the iTunes store as Apple are affiliated to the record labels.
Have you thought about YouTube or similar ?

Actually you can upload your own mixes into iTunes. They are called iMixes. You would need to convert the files to an acceptable format. AAC or MP3 are fine. Then you would need to create a playlist in iTunes and import the tracks to that playlist. Then, in the file menu, choose create iMix. Each list can have up to 100 tracks. The link below is a free online program I use to convert files. It will convert audio files as well, all for free.

Media Convert - free and on line - convert and split sound, ringtones, images, docs - H264 MP3 WMV 3GP AMR FLV SWF AMV MOV WMA AVI MPG MP4 DivX MPEG4 iPOD PSP OGG WMA AAC MP4 MPC MMF QCP KAR MIDI REALAUDIO FLAC JPG PSD DOC PDF RTF TXT ODG ODP ODS ODT (http://media-convert.com/)

Actually you can upload your own mixes into iTunes. They are called iMixes. This souded interesting so I reserached it. Unfortunately it's only about playlists:
Making your iMix playlists work in iTunes (http://docs.info.apple.com/article.html?artnum=93795)