Welcome to Slipshod Paradise.
First thing’s first, read the SR4A book, page through the wiki & supplemental books, then go make your character and post it to the Characters section (or, if you don’t want to learn Textile, email the completed character to me and get me a 20 oz soda). Providing me the itemized BP expenditures helps speed up the “GM Approval Process”, sadly, I’m not accepting bribes as an expediter.
Once you’ve made your character, or perhaps, even before you do, check out the House Rules and More On pages, as they provide additional information about the rules as we’re interpreting them and the world as we understand it. Hopefully, if you read these sections and the SR4A book, it should answer most questions before you have to ask them.