We should probably have a page or a series of well-written answers for people that have literally just found this forum for the first time. At first, it's massively overwhelming and there's although there is all the information you could ever need here, it's the "Getting Started" bit that people seem to really struggle with.
I always use the comparison that the ECU is like a large Encyclopedia. When you want to find something, you look up the contents page and find what you want and go to that page. However, with no contents page, you have no real understanding of what each page is (other than the words) so you're kind of stuck.
Your ECU currently is like that Encyclopedia in that it has no "contents page". You need to tell a bit of software (and your brain) what is stored on each page so you know what to do. That software, be it TunerPro or WinOLS is no more than just a viewer. When you define what is stored on each page (maps), you can make sense of it.
With a definition file (.kp for OLS and .xdf for TunerPro) you can work with your file. The 1.8t files are pretty well defined (if you search this site, there's a full defined CB file). My HN file is also very defined for what you'll need for it.
It's also good practice not to just flash random files onto your ECU because you can end up with a dead one; so you want to stick with what you've got. So, use the NefMoto flasher to "pull" your file off your current ECU. You'll need to choose the right ECU layout (which is in the ECU layout folder where you install the flasher) to 800bb. You can then read the ECU and save your file. Save it with the part number of the ECU or whatever you want. It's a very good habit to get into now and be neat. Store your files properly in properly named folders. When you've got files everywhere you get confused.
With your ECU read, you can go ahead and load it into TunerPro or OLS. What you'll see is just numbers, nothing more. You now need a definition file - which you'll have to define yourself if you can't find one. This is a problem, because for noobs it's very hard to understand tuning; let alone prepare a definition file. You have to get a known file and trawl through looking for patterns to get the addresses (page numbers, remember?) to give an understanding of your file. It's time consuming and hard for a novice. Hopefully your file is a defined one (pray!).
You'll need to get ECUxPlot and get ME7Logger working to give you logs. That's another thread in itself. Once you can log successfully, change fuelling. Your AUM is wideband out the box so can log fuelling accurately. Get a log with increased fuelling and make sure it follows what you expect. Now start tuning.
It's a really long process but once you're set up and have an understanding you can make strong progress. Read lots, take notes and be prepared to spend a lot of time on here.
First off, get the Flasher and get a read of your ECU. Upload it here for others (incase they need a stock read) and then look for a definition file. Either run with TunerPro or get OLS. Get a definition file; people can help you out here with requests.
Get logging working, and start tuning.