I want to edit the Account Login module, I want to add a few buttons, and remove one, where would I begin? is there a .ascx file I can edit?

Sorry if this isn't the thread for it, but I'd recommend NOT changing anything about the core DNN login module...

If you simply have to work with the style/layout, then I would recommend altering that through CSS and jQuery so that you are making visible changes that the user sees, but not altering the core module. That way when you do a DNN upgrade you're not wiping out your changes or having any special concern with upgrades.

Otherwise, if you're needing some slightly different functionality or change to buttons/functions, then that's the whole purpose of core and external modules that have been developed and worked on/improved over the years.

There are a range of well-established modules that allow you to customize and work on login actions and add great functions/perks that can be managed through the interface...

If you need to do something as straight-forward as adding and moving around buttons, changing messages, etc, I would look to the Advanced Login module from InteractiveWebs, it has the added benefit of features such as the ability to direct different roles of users to different pages upon login, custom error messaging and easy to work with templates to change the layout/look of the login

Otherwise, plenty of other modules such as Dynamic Login from DataSprings, login modules from DNNSharp for example have great features as well.

Then there's the idea to build your own, too.